Vehicle body acceleration sensor for seat belts

ABSTRACT

A vehicle body acceleration sensor suitable for being used in a retractor attached to a backrest. A vehicle body acceleration sensor ( 32 ) for use with a seat belt having a transmission device ( 39 ) which pivots a sensor case ( 30 ) about its pivot axis S according to reclining angle of a backrest ( 62 ) in synchronization with reclining action of the backrest ( 62 ) so as to retain an inertial body support surface ( 30   b ) of the sensor case ( 30 ) in an appropriate orientation. The transmission device ( 39 ) has a slide member ( 53 ) disposed in a seat portion ( 63 ), a cam plate ( 54 ) which causes to move the slide member ( 53 ) back and forth within only a pivotable range of the sensor case ( 30 ), and a wire ( 56 ) for transmitting the movement of the slide member ( 53 ) to the sensor case ( 30 ).

TECHNICAL OF THE INVENTION

The present invention relates to a vehicle body acceleration sensor foruse with a seat belt, and more particularly, to an improvement in avehicle body acceleration sensor for use with a seat belt which is usedfor a seat belt retractor attached to a backrest of a reclining seat ofa vehicle and which activates lock means for preventing withdrawal of awebbing in the event of an emergency.

BACKGROUND ART

For a seat belt apparatus for safely retaining a vehicle occupant on hisseat, there has conventionally been used an emergency lock typeretractor which has an emergency lock mechanism for physically locking aretractor through use of inertia sensing means for responding to urgentacceleration, collision, or deceleration and which safely andeffectively restrains the occupant.

Inertia sensing means used for such an emergency lock type retractorincludes a vehicle body acceleration sensor for sensing the accelerationof the vehicle body. For example, the vehicle body acceleration sensoris constructed such that, when an inertial body is moved as a result ofcollision or inclination of the vehicle body, a sensor arm provided ontop of the inertial body is pivoted, thereby activating lock means forlocking rotation in the direction in which the webbing is drawn-out froma take-up shaft around which a webbing is wound.

Recently, there have been proposed various types of vehicle body sensorsfor use with a seat belt, in which a retractor such as that mentionedpreviously is provided within a backrest of a reclining seat and which,even when the backrest is titled, can be activated in the same way aswhen the backrest is not reclined.

For example, like vehicle body acceleration sensors described in GermanPatent Publication No. 4,032,157, U.S. Pat. No. 4,978,087, and JapanesePatent Unexamined Publications No. Hei.1-202553 and No. Hei.3-148350,there have already been proposed various types of vehicle bodyacceleration sensors which are provided with transmission means, such asa flexible shaft or a gear device, for controlling the angle of a sensorcase by pivotal movement of the sensor case about its pivot insynchronization with reclining action of a backrest, in such a way thatan inertial body support surface formed on the sensor case is retainedin an appropriate position with respect to the sensor case pivotallysupported by a retractor base regardless of reclining angle of thebackrest, or are provided with rotary drive means such as a servo motorwhich rotatively actuates the sensor case according to a reclining angleof the backrest.

By means of the seat belt apparatus having such a structure, even whenthe backrest is inclined or slid between the full forward and full backpositions, the positional relationship between a shoulder belt of thewebbing and a backrest remains unchanged, thereby ensuring superiorrestraining performance.

In a case where the sensor case is rotatively actuated by means of aservo motor, or the like, according to the reclining angle of thebackrest, use of a motor adds to component costs, results in an increasein the number of components, and renders the structure of the seat beltapparatus complicated, thus leading to an increase in manufacturingcosts.

In a case where the sensor case is rotated, through use of thetransmission means, about its pivot in synchronization with thereclining action of the backrest according to the reclining angle of thebackrest, the pivotable range of the sensor case is set so as tocorrespond to an optimum working range of the retractor which isattached to the backrest and is capable of appropriately restraining theoccupant by means of webbing. However, the optimum working range of theretractor generally constitutes a portion of the reclining range of thebackrest and is narrower than the reclining range. For this reason, in acase where the sensor case is rotatively actuated by means oftransmission means—such as a flexible shaft or a gear device—interposedbetween the sensor case and seat hardware, when the backrest is reclinedbeyond the optimum working range of the retractor, the sensor case isactuated by way of the transmission means, thereby resulting ininterference with another component or straining and damaging the sensorcase.

To prevent such a problem, the angle at which the backrest is reclinedis limited so as to match the pivotable range of the sensor case, withthe result that the range of inclination of the backrest becomesnarrower than that of a seat having not a built-in retractor, therebyrendering a vehicle seat very difficult to use.

In contrast, in a case where the sensor case is arranged so as to beable to pivot in synchronization with the reclining action of thebackrest even when the backrest in reclined beyond the optimum workingrange of the seat belt, a large space is required for movement of thesensor case, thereby rendering the retractor large.

An angle sensing means provided in the transmission means for sensingthe inclination of the backrest includes an angle sensing means forsensing the inclination of the backrest by sensing relative rotationbetween a member disposed in a seat and a member which is provided onthe side of a recliner mechanism (a hinge mechanism of the seat) facingthe backrest and which pivots together with the backrest.

Since the angle sensing means pivots in agreement with the pivotalmovement of the backrest, the pivot of the angle sensing means isdesirably placed in line with the reclining pivot of the backrest. Asshown in FIG. 78, if a reclining pivot O of the backrest does not matcha pivot Q of the angle sensing means, a pivotable angle θ of thebackrest does not match a pivotable angle α of the angle sensing meansat, e.g., a point V (a position where the angle sensing means is mountedon the backrest), thereby rendering impossible correct adjustment of theorientation of the sensor case.

In order to cause the reclining pivot of the backrest to coincide withthe pivot of the angle sensing means, the reclining mechanism on whichthe angle sensing means is mounted and the angle sensing means must bemanufactured with a high degree of dimensional precision. Both thereclining mechanism and the angle sensing means require a large numberof components, thereby becoming expensive.

Accordingly, the object of the present invention is to provide a vehiclebody acceleration sensor to be disposed in a retractor mounted on abackrest, and more particularly, to provided a vehicle body accelerationsensor for use with a seat belt which is capable of reliably and stablysensing the acceleration of a vehicle body regardless of the recliningangle of the backrest and which enables a reduction in manufacturingcosts by employment of a simple mechanism.

DISCLOSURE OF THE INVENTION

The foregoing object of the present invention is achieved by a vehiclebody acceleration sensor for use with a seat belt comprising:

a sensor case which is supported in a movable manner by a retractor basemounted on a backrest of a reclining vehicle seat;

a sensor arm which is pivotally mounted on the sensor case or theretractor base so as to move lock means between a first position wherethe lock means is actuated and a second position where the lock meansbecomes inoperative, the lock means preventing a take-up shaft, aroundwhich a webbing is wound, from rotating in a direction in which thewebbing is drawn-out;

an inertial body which moves in relation to an inertial body supportsurface of the sensor case upon receipt of a velocity change of greaterthan a predetermined value, thereby moving the sensor arm to the firstposition; and

transmission means for moving the sensor case in synchronization withreclining action of the backrest according to a reclining angle of thebackrest so that the inertial body support member is held at anappropriate orientation regardless of reclining angle of the backrest,wherein the lock means is actuated by means of movement of the inertialbody caused when a predetermined acceleration acts on the vehicle body.

By means of the foregoing structure of the sensor case, when theinclination of the backrest is changed, the inertial body supportsurface is held at an appropriate position by means of transmissionmeans which is actuated in synchronization with reclining action of thebackrest. The vehicle body acceleration sensor can properly operate evenwhen the backrest is in another reclined position and can sense theacceleration of the vehicle body without fail.

The object of the present invention is also achieved by a vehicle bodyacceleration sensor for use with a seat belt including:

a sensor case which is supported in a movable manner by a retractor basemounted on a backrest of a reclining vehicle seat;

a sensor arm which is pivotally mounted on the sensor case or theretractor base so as to move lock means between a first position wherethe lock means is actuated and a second position where the lock meansbecomes inoperative, the lock means preventing a take-up shaft, aroundwhich a webbing is wound, from rotating in a direction in which thewebbing is drawn-out;

an inertial body which moves in relation to an inertial body supportsurface of the sensor case upon receipt of a velocity change of greaterthan a predetermined value, thereby moving the sensor arm to the firstposition; and

transmission means for moving the sensor case in synchronization withreclining action of the backrest according to a reclining angle of thebackrest so that the inertial body support member is held in anappropriate orientation regardless of reclining angle of the backrest,wherein the lock means is actuated by means of movement of the inertialbody caused when a predetermined acceleration acts on the vehicle body,the vehicle body acceleration sensor being characterized by that

the transmission means includes a synchronous movement cancelationmechanism capable of canceling the movement of the sensor case which isin synchronization with the reclining action of the backrest.

By means of the foregoing structure of the sensor case, when theinclination of the backrest is changed, the inertial body supportsurface is held at an appropriate position by means of transmissionmeans which is actuated in synchronization with reclining action of thebackrest. The vehicle body acceleration sensor can properly operate evenwhen the backrest is in another reclined position and can sense theacceleration of the vehicle body without fail.

When the backrest is reclined beyond the optimum working range of theseat belt, the synchronous movement cancelation mechanism can cancel thepivotal movement of the sensor case in synchronization with thereclining action of the backrest. Therefore, the reclining angle of thebackrest is prevented from being limited by the pivotable range of thesensor case. Further, the sensor case is prevented from beingunnecessarily rotated in synchronization with the reclining action ofthe backrest, thereby preventing the retractor from becoming bulky.

In this case, the pivotable range of the sensor case is set so as tobecome slightly larger than the reclining range of the backrest withinthe optimum working range of the seat belt, so as to prevent damage tothe sensor case.

More preferably, the transmission means comprises

a slide member movably disposed in a seat portion of the reclining seat;

a cam plate which causes the slide member to advance or recede withinonly the pivotable range of the sensor case according to the recliningangle of the backrest; and

a flexible transmission member, one end of which is connected to theslide member and the other end of which is connected to the sensor caseand which transmits the movement of the slide member to the sensor case.As a result, the transmission member that retains the inertial bodysupport surface in an optimal state in synchronization with thereclining action of the backrest is made up of a simple mechanismcomprising the slide member, the cam plate, and the flexibletransmission member and does not require an expensive component such asa motor. Therefore, a rise in manufacturing costs can be prevented.

More preferably, the transmission member comprises

a transmission member which is actuated in synchronization with thereclining action of the backrest; and

a synchronous movement cancelation mechanism which is interposed atleast between a retractor-side joint section of the transmission sectionand the sensor case and which prevents the sensor case from moving insynchronization with the reclining action of the backrest when thebackrest is reclined beyond the optimum working range of the seat belt.There can be prevented complication of a mechanism which is provided onthe seat reclining pivot of the backrest and which transmits thereclining action of the backrest to a seat-reclining-pivot-side jointsection of the transmission member to thereby actuate the sensor case.Consequently, the vehicle body acceleration sensor can cope with aplurality of types of seats by merely minor modification of theretractor.

More preferably, the synchronous movement cancelation mechanismcomprises a slider which is joined to the sensor case by means of theretractor-side end section of the transmission member and has a range ofmovement limited to the pivotable range of the sensor case that is setto the optimum working range of the set belt; and an elastic memberwhich is interposed between the slider and the retractor-side jointsection of the transmission member and which is resiliently deformablein the direction of movement of the slider upon receipt of a load ofgreater than a predetermined value. When the backrest is reclined beyondthe optimum working range of the seat belt, the elastic member deflectsand absorbs the displacement of the transmission member, thereby readilypreventing the sensor case from pivoting in synchronization with thereclining action of the backrest.

More preferably, the synchronous movement cancelation mechanismcomprises a gear with a cam which engages with the retractor-side jointof the transmission section and is rotated; and the sensor case whichfollows the cam of the gear and pivots within a pivotable range which isset so as to correspond to the optimum working range of the seat belt.When the backrest is reclined beyond the optimum working range of theseat belt, the sensor case can be readily prevented from pivoting insynchronization with the backrest.

The object of the present invention is also achieved by a vehicle bodyacceleration sensor for use with a seat belt including:

a sensor case which is movably supported by a retractor base mounted ona backrest of a reclining vehicle seat;

a sensor arm which is pivotally mounted on the sensor case or theretractor base so as to move lock means between a first position wherethe lock means is actuated and a second position where the lock meansbecomes inoperative, the lock means preventing a take-up shaft, aroundwhich a webbing is wound, from rotating in a direction in which thewebbing is drawn-out;

an inertial body which moves in relation to an inertial body supportsurface of the sensor case upon receipt of a velocity change of greaterthan a predetermined value, thereby moving the sensor arm to the firstposition; and

transmission means for moving the sensor case in synchronization withreclining action of the backrest according to a reclining angle of thebackrest so that the inertial body support member is held in anappropriate orientation regardless of reclining angle of the backrest,wherein the lock means is actuated by means of movement of the inertialbody caused when a predetermined acceleration acts on the vehicle body,the vehicle body acceleration sensor being characterized by

the transmission means including a cam plate whose cam surface extendsin the circumferential direction from the seat reclining pivot of thebackrest, and a transmission member which follows the cam surface of thecam plate and pivots the sensor case in conjunction with the recliningaction of the backrest.

By means of the foregoing structure of the sensor case, when theinclination of the backrest is changed, the transmission member followsthe cam surface to thereby pivot the sensor case in synchronization withthe reclining action of the backrest. Accordingly, the inertial bodysupport surface is retained in an appropriate orientation. The vehiclebody acceleration sensor can properly operate regardless of the reclinedangle of the backrest and can sense the acceleration of the vehicle bodywithout fail.

The transmission member is made up of a simple mechanism comprising atransmission member such as a rod member having a simple shape or aflexible transmission member and a cam plate, both of which can bereadily and inexpensively mass-produced by press-working of platematerial, and does not require an expensive component such as a motor.Therefore, a rise in manufacturing costs can be prevented.

By provision of cam plates having different cam profiles, there may beproduced a vehicle body acceleration sensor of superior versatilitywhich can be used with a plurality of types of reclining seats and seatbelt retractors through selection of an appropriate one of the camplates.

More preferably, the cam surface of the cam plate comprises asynchronous movement area in which the sensor case is pivoted insynchronization with the reclining action of the backrest within onlythe optimum working range of the seat belt, and non-synchronous movementareas in which the sensor case is not pivoted in synchronization withthe reclining action of the backrest. When the backrest is reclinedwithin the optimum working range of the seat belt, the transmissionmember follows the synchronous movement area of the cam surface andcauses the sensor case to pivot in synchronization with the recliningaction of the backrest. In contrast, when the backrest is reclinedbeyond the optimum working range of the seat belt, the transmissionmember follows a non-synchronous movement area of the cam surface andprevents the sensor case from pivoting in synchronization with thereclining action of the backrest. Accordingly, the range of recliningangle of the backrest is not limited by the pivotable range of thesensor case. Further, the sensor case is not required to pivot more thannecessary so as to stay in synchronization with the reclining action ofthe backrest, thereby preventing the retractor from becoming bulky.

Here, the pivotable range of the sensor case is set so as to becomeslightly wider than the range of reclining angle of the backrest withinthe optimum working range of the seat belt so as to prevent damage tothe sensor case.

More preferably, a cam contact section formed on the cam-plate-side endsection of the transmission member which moves back and forth toward thecam surface of the cam plate is set so as to move back and forth in sucha direction as to impart an optimum pressing force on the entire surfaceof the cam surface with which the cam contact section makes slidablecontact. Consequently, the cam-plate-side end section of thetransmission member can be prevented from being twisted and protectedfrom excessive force.

More preferably, the cam plate is fixed on a seat portion of thereclining seat, and the cam-plate-side end section of the transmissionmember is fixed on the backrest so as to be able to move back and forthtoward the cam surface of the cam plate. As a result, the transmissionmember is prevented from being bent every time the backrest is reclined,thereby preventing deterioration of durability of the transmissionmember.

More preferably, the transmission means comprises a cam plate which hasan inner peripheral cam surface and extends in the circumferentialdirection of the seat reclining pivot of the backrest; a follower whichis provided on the inner peripheral cam surface of the cam plate so asto be able to move back and forth; and a transmission member which has acam-plate-side end section joined to the follower and a retractor-sidesection joined to the sensor case and which transmits the forward andbackward movement of the follower to the sensor case. When the backrestis reclined, the follower that follows the inner peripheral cam surfacepivots the sensor case in synchronization with the reclining action ofthe backrest by way of the transmission member, thereby retaining theinertial body support surface in an appropriate orientation. As aresult, regardless of the reclining angle of the backrest, the vehiclebody acceleration sensor can operate appropriately and can sense theacceleration of the vehicle body without fail.

The transmission member is made up of a simple mechanism comprising atransmission member such as a rod member having a simple shape or afollower and a cam plate which can be readily and inexpensivelymass-produced by press-working of plate material, and does not requirean expensive component such as a motor. Therefore, a rise inmanufacturing costs can be prevented.

By provision of cam plates having different inner peripheral camsurfaces, there may be produced a vehicle body acceleration sensor ofsuperior versatility which can be used with a plurality of types ofreclining seats and seat belt retractors through selection of anappropriate one of the cam plates.

More preferably, the inner peripheral cam surface of the cam plate isprovided with only the synchronous movement area in which the sensorcase is pivoted in synchronization with the reclining action of thebackrest within only the optimum working range of the seat belt.Alternatively, the inner peripheral cam surface is provided with asynchronous movement area in which the sensor case is pivoted insynchronization with the reclining action of the backrest within onlythe optimum working range of the seat belt, and non-synchronous movementareas in which the sensor case is prevented from pivoting insynchronization with the reclining action of the backrest. As a result,when the backrest is reclined beyond the optimum working range of theseat belt, the follower is disengaged from the inner peripheral camsurface or follows a non-synchronous movement area of the innerperipheral cam surface, so that the sensor case is prevented frompivoting in synchronization with the reclining action of the backrest.Accordingly, the reclining angle of the backrest is not limited by thepivotable range of the sensor case. Further, the sensor case is notrequired to pivot more than necessary in synchronization with thereclining action of the backrest, thereby preventing the retractor frombecoming bulky.

Here, the pivotable range of the sensor case is set so as to becomeslightly wider than the range of reclining angle of the backrest withinthe optimum working range of the seat belt so as to prevent damage tothe sensor case.

More preferably, the follower has a roller which moves over the innerperipheral cam surface in a rotatable manner, and hence frictionalresistance between the inner peripheral cam surface and the follower canbe reduced, thereby enabling smooth forward and backward movement of thefollower.

More preferably, the cam plate is mounted on the seat portion of thereclining seat, and the follower is fixed on the backrest so as to beable to move back and forth along the inner peripheral cam surface ofthe cam plate. Therefore, the transmission member is prevented frombeing bent every time the backrest is reclined, thereby preventingdeterioration of durability of the transmission member.

The object of the present invention is also achieved by a vehicle bodyacceleration sensor for use with a seat belt including:

a sensor case which is movably supported by a retractor base mounted ona backrest of a reclining vehicle seat;

a sensor arm which is pivotally mounted on the sensor case or theretractor base so as to move lock means between a first position wherethe lock means is actuated and a second position where the lock meansbecomes inoperative, the lock means preventing a take-up shaft, aroundwhich a webbing is wound, from rotating in a direction in which thewebbing is drawn-out;

an inertial body which moves in relation to an inertial body supportsurface of the sensor case upon receipt of a velocity change of greaterthan a predetermined value, thereby moving the sensor arm to the firstposition; and

transmission means for moving the sensor case in synchronization withreclining action of the backrest according to a reclining angle of thebackrest so that the inertial body support member is held in anappropriate orientation regardless of reclining angle of the backrest,wherein the lock means is actuated by means of movement of the inertialbody caused when a predetermined acceleration acts on the vehicle body,the vehicle body acceleration sensor being characterized by

the transmission means including a transmission member which can bewrapped around a take-up member provided concentrically and in line withthe seat reclining pivot of the backrest, and the sensor case beingpivoted in agreement with the amount of the transmission member which iswrapped around the take-up member in association with the recliningaction of the backrest.

By means of the foregoing structure of the sensor case, when thetransmission member is wrapped around the take-up member, the sensorcase is pivoted in agreement with the amount of the transmission memberwhich is wrapped around the take-up member, so that the inertial bodysupport surface is retained in an appropriate orientation. Accordingly,the vehicle body acceleration sensor can properly operate regardless ofthe reclining angle of the backrest and can sense the acceleration ofthe vehicle body without fail.

More preferably, when the backrest is reclined forwardly beyond an areawhich enables an occupant to use the seat, the transmission member isprevented from being wrapped around the take-up member. As a result, thesensor case is prevented from pivoting in synchronization with thebackrest and remains stationary. Accordingly, it is possible toeliminate a need for provision of a space for pivotal movement of thesensor case within the retractor corresponding to a range of recliningaction of the backrest in which the occupant cannot use the seat,thereby rendering the retractor compact.

More preferably, the end member of the transmission member facing thevehicle body acceleration sensor is wrapped about the a take-up shaft,and the take-up member pivots the sensor case in agreement with theamount of the transmission member that is wrapped around the take-upmember, by causing the winding radius of the end member of thetransmission member facing the take-up member to match the windingradius of the end member of the transmission member facing the vehiclebody acceleration sensor. A take-up surface of the take-up member can beformed into a simple circular arc shape.

The object of the present invention is also achieved by a vehicle bodyacceleration sensor for use with a seat belt including:

a sensor case which is movably supported by a retractor base mounted ona backrest of a reclining vehicle seat;

a sensor arm which is pivotally mounted on the sensor case or theretractor base so as to move lock means between a first position wherethe lock means is actuated and a second position where the lock meansbecomes inoperative, the lock means preventing a take-up shaft, aroundwhich a webbing is wound, from rotating in a direction in which thewebbing is drawn-out;

an inertial body which moves in relation to an inertial body supportsurface of the sensor case upon receipt of a velocity change of greaterthan a predetermined value, thereby moving the sensor arm to the firstposition; and

transmission means for moving the sensor case in synchronization withreclining action of the backrest according to a reclining angle of thebackrest so that the inertial body support member is held in anappropriate orientation regardless of reclining angle of the backrest,wherein the lock means is actuated by means of movement of the inertialbody caused when a predetermined acceleration acts on the vehicle body,the vehicle body acceleration sensor being characterized by thetransmission means having angle sensing means for sensing the recliningangle of the backrest by detection of relative turning movement betweena member which is provided on the backrest and pivots in conjunctionwith the backrest and a member which is provided in a seat portion; and

a seat pivot shaft placed in line with the seat reclining pivot of thebackrest and a pivot shaft of the angle sensing means being providedconcentrically and in line with the seat reclining pivot of thebackrest, the pivot shafts having irregularities which mesh each other.

By means of the foregoing configuration, the irregularities formed onthe seat pivot shaft of the backrest and the irregularities formed onthe pivot shaft of the angle sensing means bring the seat recliningpivot of the backrest in alignment with the pivotable axis of the anglesensing means.

Consequently, since the reclining angle of the backrest and the pivotingangle of the angle sensing means match, the transmission means cancorrectly adjust the orientation of sensing means of the sensor case.Since only requirement is to form irregularities, which mesh each other,on the seat pivot shaft of the backrest and the pivot shaft of the anglesensing means, an increase in manufacturing costs can be prevented.

More preferably, holes used for mounting the angle sensing means areformed so as to be large enough to allow offset of the pitch at whichthe angle sensing means is attached to the mount section of the seatportion. Therefore, formation of mount holes does not require a highdegree of dimensional precision, thereby enabling a reduction inmanufacturing costs.

Accordingly, there can be provided a vehicle body acceleration sensorfor use with a seat belt which is attached to a retractor positioned ina backrest, is capable of sensing the acceleration of the vehicle bodyregardless of the reclining angle of the backrest without fail, andenables a reduction in manufacturing costs by employment of a simplestructure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic side view showing a reclining seat on which ismounted a seat belt retractor having a vehicle body acceleration sensoraccording to a first embodiment of the present invention;

FIG. 2 is a side view showing the seat belt retractor shown in FIG. 1;

FIG. 3 is a front view showing the seat belt retractor shown in FIG. 1;

FIG. 4 is a side view showing the reclining seat shown in FIG. 1 when abackrest of the reclining seat is reclined to the most backwardlyreclined position within a working range of a seat belt;

FIG. 5 is a side view of the seat belt retractor showing the state ofthe vehicle body acceleration sensor when the backrest shown in FIG. 4is reclined;

FIG. 6 is a side view showing the reclining seat shown in FIG. 1 whenthe backrest of the reclining seat is reclined to the most backwardlyreclined position;

FIG. 7 is a side view showing the reclining seat shown in FIG. 1 whenthe backrest of the reclining seat is reclined to the most forwardlyreclined position;

FIG. 8 is a side view of the seat belt retractor showing the state ofthe vehicle body acceleration sensor when the backrest shown in FIG. 7is reclined;

FIG. 9 is a schematic side view showing a reclining seat, wherein a seatbelt retractor having a vehicle body acceleration sensor for use with aseat belt according to a second embodiment is incorporated in abackrest;

FIG. 10 is a side view of the retractor showing the state of the vehiclebody acceleration sensor when the backrest shown in FIG. 9 is reclinedto the most forwardly reclined position within an optimum working rangeof the seat belt;

FIG. 11 is a side view showing the state of the side of the transmissionmeans facing a seat reclining pivot when the backrest shown in FIG. 9 ispositioned in the most forwardly reclined position within the optimumworking range of the seat belt;

FIG. 12 is a side view showing the state of the side of the transmissionmeans facing a seat reclining pivot when the backrest shown in FIG. 9 ispositioned in the most backwardly reclined position within the optimumworking range of the seat belt;

FIG. 13 is a side view showing the state of the side of the transmissionmeans facing a seat reclining pivot when the backrest shown in FIG. 9 ispositioned forward of the most forwardly reclined position within theoptimum working range of the seat belt;

FIG. 14 is a side view showing the state of the side of the transmissionmeans facing a seat reclining pivot when the backrest shown in FIG. 9 ispositioned backward of the most backwardly reclined position within theoptimum working range of the seat belt;

FIG. 15 is a side view of a seat belt retractor showing the state of thevehicle body acceleration sensor for use with a seat belt according tothe second embodiment when the backrest shown in FIG. 9 is positionedbackward of the most backwardly reclined position within the optimumworking range of the seat belt;

FIG. 16 is an enlarged cross-sectional view of the principle elementsshowing the state of a retractor-side portion of the transmission meansin the vehicle body acceleration sensor shown in FIG. 15;

FIG. 17 is a side view showing the set belt retractor equipped with avehicle body acceleration sensor for use with a seat belt according to athird embodiment of the present invention;

FIG. 18 is a side view showing the configuration of aseat-reclining-pivot-side section of the transmission means in thevehicle body acceleration sensor according to the third embodiment;

FIG. 19 is an enlarged perspective view of the principle elementsshowing engagement between a sensor case and a cam groove formed in aworm wheel which is attached to the retractor-side portion of thetransmission means in the vehicle body acceleration sensor according tothe third embodiment;

FIG. 20 is an enlarged front view showing the worm wheel attached to theretractor-side portion of the transmission means in the vehicle bodyacceleration sensor according to the third embodiment;

FIG. 21 is a side view showing a seat belt retractor equipped with avehicle body acceleration sensor for use with a seat belt according to afourth embodiment of the present invention;

FIG. 22 is an enlarged front view of the worm wheel shown in FIG. 21;

FIG. 23 is a side view of a retractor showing the vehicle bodyacceleration sensor shown in FIG. 21 when the sensor is pivoted beyondthe most backwardly reclined position of the optimum working range ofthe seat belt;

FIG. 24 is a schematic side view showing a reclining seat, wherein aseat belt retractor having a vehicle body acceleration sensor for usewith a seat belt according to a fifth embodiment is incorporated in abackrest;

FIG. 25 is a side view showing the seat belt retractor shown in FIG. 24;

FIG. 26 is a fragmentary sectional view showing the seat belt retractorshown in FIG. 24;

FIG. 27 is an enlarged view showing the principle elements oftransmission means in the vehicle body acceleration sensor shown in FIG.24;

FIG. 28 is a side view of the reclining seat shown in FIG. 24 when thebackrest of the reclining seat is reclined to the most backwardlyreclined position within the working range of the seat belt;

FIG. 29 is a side view of the seat belt retractor showing the vehiclebody acceleration sensor when the backrest shown in FIG. 28 is reclined;

FIG. 30 is an enlarged view of the principle elements showing the stateof transmission means of the vehicle body acceleration sensor when thebackrest shown in FIG. 28 is reclined;

FIG. 31 is a side view of the reclining seat shown in FIG. 24 when thebackrest of the reclining seat is reclined to the most forwardlyreclined position within the working range of the seat belt;

FIG. 32 is a side view of the seat belt retractor showing the state ofthe vehicle body acceleration sensor when the backrest shown in FIG. 31is reclined;

FIG. 33 is an enlarged view of the principle elements showing the stateof transmission means of the vehicle body acceleration sensor when thebackrest shown in FIG. 31 is reclined;

FIG. 34 is a side view of the reclining seat shown in FIG. 24 when thebackrest of the reclining seat is reclined to the most backwardlyreclined position within the working range of the seat belt;

FIG. 35 is side view of a seat belt retractor showing the state of thevehicle body acceleration sensor when the backrest shown in FIG. 34 isreclined;

FIG. 36 is an enlarged view of the principle elements showing the stateof transmission means of the vehicle body acceleration sensor when thebackrest shown in FIG. 34 is reclined;

FIG. 37 is a schematic side view showing a reclining seat, wherein aseat belt retractor having a vehicle body acceleration sensor for usewith a seat belt according to a sixth embodiment is incorporated in abackrest;

FIG. 38 is a side view showing the seat belt retractor shown in FIG. 37;

FIG. 39 is an enlarged view of the principle elements showing thetransmission means shown in FIG. 37;

FIG. 40 is an enlarged view of the principle elements showing thefollower shown in FIG. 39;

FIG. 41 is a schematic side view showing a reclining seat, wherein aseat belt retractor having a vehicle body acceleration sensor for usewith a seat belt according to a seventh embodiment is incorporated in abackrest;

FIG. 42 is a fragmentary sectional view showing the seat belt retractorshown in FIG. 41;

FIG. 43A is a side view showing the seat belt retractor shown in FIG.41;

FIG. 43B is an enlarged view of the principle elements showing thetransmission means of the vehicle body acceleration sensor shown in FIG.41;

FIG. 44 is an exploded perspective view showing the transmission meansof the vehicle body acceleration sensor shown in FIG. 41;

FIG. 45 is a fragmentary sectional view showing the transmission meansshown in FIG. 44;

FIG. 46 is a side view showing the state of the reclining seat shown inFIG. 41 when the backrest of the reclining seat is reclined to the mostbackwardly reclined position;

FIG. 47A is a side view illustrating the seat belt retractor of thebackrest shown in FIG. 46;

FIG. 47B is an enlarged view of the principle elements showing thetransmission means when the backrest is reclined as shown in FIG. 46;

FIG. 48 is a side view of the reclining seat shown in FIG. 41 when thebackrest of the reclining seat is reclined forwardly in excess of arange of reclining action of the backrest in which the occupant can usethe seat;

FIG. 49A is a side view showing the seat belt retractor when thebackrest is reclined as shown in FIG. 48;

FIG. 49B is an enlarged view of the principle elements showing thetransmission means when the backrest is reclined as shown in FIG. 48;

FIG. 50 is an enlarged view of the principle elements showing amodification of the cam plate;

FIG. 51 is an enlarged view of the principle elements showing amodification of the cam plate;

FIG. 52 is a schematic side view showing a reclining seat, wherein aseat belt retractor having a vehicle body acceleration sensor for usewith a seat belt according to an eighth embodiment is incorporated in abackrest;

FIG. 53 is an exploded perspective view showing a take-up member shownin FIG. 52;

FIG. 54 is a schematic perspective view showing the area of thereclining seat where the take-up member is attached;

FIG. 55 is a side view showing the seat belt retractor shown in FIG. 52;

FIG. 56 is a cross-sectional view showing the seat belt retractor shownin FIG. 52;

FIG. 57A is a side view showing a reclining seat when a backrest is setto the most forwardly reclined position within the range of recliningaction of the backrest in which an occupant can take the seat;

FIG. 57B is a side view showing the take-up member from which a cover isremoved when the backrest is in the position shown in FIG. 57A;

FIG. 57C is a side view showing a retractor when the backrest is in theposition shown in FIG. 57A;

FIG. 58A is a side view showing a reclining seat when a backrest isreclined to the most backwardly reclined position (i.e., a full-flatposition);

FIG. 58B is a side view showing a take-up member from which a cover isremoved when the backrest is in the full-flat position;

FIG. 58C is a side view showing a retractor when the backrest is in thefull-flat position;

FIG. 59A is a side view showing a reclining seat when a backrest isreclined to a forward position beyond a range of reclining angle of thebackrest in which an occupant can take the seat;

FIG. 59B is a side view showing a take-up member from which a cover isremoved when the backrest is reclined as shown in FIG. 59A;

FIG. 59C is a side view showing a retractor when the backrest isreclined as shown in FIG. 59A;

FIG. 60 is a schematic side view showing a reclining seat, wherein aseat belt retractor having a vehicle body acceleration sensor for usewith a seat belt according to an ninth embodiment is incorporated in abackrest;

FIG. 61 is a side view showing a wire lever shown in FIG. 60;

FIG. 62 is an enlarged perspective view showing the principle elementsof transmission means shown in FIG. 60;

FIG. 63 provides a front view and a side view, both of which show a wiretake-up member shown in FIG. 60;

FIG. 64 is a side view showing a retractor shown in FIG. 60;

FIG. 65 is a cross-sectional view showing the retractor shown in FIG.60;

FIG. 66A is a side view showing a reclining seat when a backrest isreclined to the most forward position within a range of reclining actionof the backrest in which an occupant can take the seat;

FIG. 66B is a side view showing a wire take-up member when the backrestis reclined as shown in FIG. 66A;

FIG. 66C is a side view showing a retractor when the backrest isreclined as shown in FIG. 66A;

FIG. 67A is a side view showing a reclining seat when a backrest isreclined to the most backwardly reclined position (i.e., a full-flatposition);

FIG. 67B is a side view showing a wire take-up member from which a coveris removed when the backrest is in the full-flat position;

FIG. 67C is a side view showing a retractor when the backrest is in thefull-flat position;

FIG. 68A is a side view showing a reclining seat when a backrest isreclined forwardly from the state such as that shown in FIG. 66;

FIG. 68B is a side view showing a wire take-up member when the backrestis reclined as shown in FIG. 68A;

FIG. 68C is a side view showing a retractor when the backrest isreclined as shown in FIG. 68A;

FIG. 69 is a front view showing the seat belt retractor shown in FIG. 60when a sensor cover is attached to the retractor;

FIG. 70 is a schematic side view showing a reclining seat, wherein aseat belt retractor having a vehicle body acceleration sensor for usewith a seat belt according to a tenth embodiment is incorporated in abackrest;

FIG. 71 is a side view showing the seat belt retractor shown in FIG. 70;

FIG. 72 is a cross-sectional view showing the principle elements of theseat belt retractor shown in FIG. 71;

FIG. 73 is an enlarged fragmentary view showing the reclining seat shownin FIG. 70;

FIG. 74 provides a schematic side view and a front view, both of whichshow angle sensing means shown in FIG. 70;

FIG. 75 is an exploded perspective view showing the angle sensing meansshown in FIG. 74;

FIG. 76 is an enlarged fragmentary view showing a reclining seat relatedto a modification of the angle sensing means;

FIG. 77 is a schematic side view showing a modification of the anglesensing means and a cross-sectional view of the same when viewed indirection of arrow K—K; and

FIG. 78 is a schematic representation for describing a conventionaltechnique.

BEST MODES FOR CARRYING OUT THE INVENTION

A vehicle body acceleration sensor for use with a seat belt according toone embodiment of the present invention will be described in detailhereinbelow with reference to the accompanying drawings.

FIG. 1 is a schematic side view showing a reclining seat, in which aseat belt retractor 100 equipped with a vehicle body acceleration sensor32 according to a first embodiment of the present invention isincorporated in a backrest 62.

As shown in FIG. 1, the seat belt retractor 100 is built in the backrest62 of the reclining seat 61 mounted on a vehicle body. The backrest 62is connected to a seat portion 63 so as to be pivotal about a seatreclining pivot (a backrest reclining pivot) 71 extending in thewidthwise direction of the vehicle body. According to the physique of anoccupant, the inclination of the backrest 62 is adjusted.

As shown in FIGS. 2 and 3, the seat belt retractor 100 comprises asubstantially cylindrical bobbin 2 around which a webbing 70 is wound; atake-up shaft 4 which is inserted into the bobbin 2, is rotativelysupported by means of a retractor base 1, and has at one end thereof(i.e., on the right-side of the take-up shaft 4 shown in FIG. 3) a latchplate 4 a formed from a ratchet wheel; and an emergency lock mechanism300 which, in the event of an emergency, prevents rotation of the latchplate 4 a in a direction in which the webbing 70 is drawn-out. Thewebbing 70 withdrawn from the retractor 100 by way of a slot 64 formedin the backrest 62 restraints the occupant.

The retractor base 1 mounted on a frame member (not shown) of thebackrest 62 is formed from a metal plate through press molding such thatthe majority of the retractor base 1 assumes a substantially angularC-shaped cross section. The take-up shaft 4 fitted into the bobbin 2 isrotatable and sandwiched between both sides plates 1 a and 1 b of theretractor base 1. The end of the take-up shaft 4 that passes through theside plate 1 b of the retractor base 1 is provided with a known take-upspring device 40. At all times, the take-up spring device 40 urges thebobbin 2, in the direction in which the webbing 70 is taken up, by wayof the take-up shaft 4.

According to the present invention, the emergency lock mechanism 300that, in the event of an emergency prevents rotation of the take-upshaft 4 in the direction in which the webbing 70 is drawn-out may employany of various known structures. For example, according to the firstembodiment, a ratchet wheel 19 serving as a lock actuation means rotatesso as to lag behind the take-up shaft 4, so that a ratchet cup 13 causesa pole 11 to engage the latch plate 4 a, thereby preventing rotation ofthe take-up shaft 4 in the direction in which the webbing 70 isdrawn-out. The pole 11 is rotatively supported by means of a pole pin 10fitted into the side plate 1 a.

The vehicle body acceleration sensor 32 according to the firstembodiment is provided below the ratchet wheel 19.

As shown in FIGS. 2 and 3, the vehicle body acceleration sensor 32comprises a sensor arm 31, a sensor case 30, an inertial body 33, ahanger 38, and transmission means 39.

The hanger 38 is a support frame fixed on the side plate 1 a of theretractor base 1 and comprises an arm support section 35 for rotativelysupporting the base end of the sensor arm 31 and a case support section36 for rotatively supporting the sensor case 30. In the case of thefirst embodiment, the support arm section 35 corresponds to a bearinghole into which is rotatively fitted a pin 31 a provided at the base endof the sensor arm 31. The center of rotation of the sensor case 30passes through the center of a spherical inertial body 38.

The pin 31 a provided at the base end of the sensor arm 30 is rotativelysupported by the arm support section 35 of the hanger 38 and is attachedto the side plate 1 a of the retractor base 1 by way of the hanger 38.While being attached to the retractor base 1 by way of the hanger 38,the sensor arm 31 can pivot about the shaft 31 from a first position toa second position. In the first position, a leading edge 31 b engagesteeth 19 a of the ratchet wheel 19, thereby actuating a lock means so asto prevent rotation of the take-up shaft 4 in the direction in which thewebbing 70 is drawn-out. In the second position, the leading edge 31 bis disengaged from the teeth 19 a, thereby rendering the lock meansinoperative. The expression “lock means” used in the present inventionsignifies the emergency lock mechanism from which the vehicle bodyacceleration sensor is excluded.

When the leading edge 31 b of the sensor arm 31 engages the teeth 19 aof the ratchet wheel 19, the ratchet wheel 19 rotates so as to lagbehind the take-up shaft 4, so that the pole 11 engages the latch plate4 a by way of the latch cup 13 to thereby prevent rotation of thetake-up shaft 4 in the direction in which the webbing 70 is drawn-out.

An inertial body support surface 30 b on which the inertial body 33 isplaced is provided at the inner bottom of the sensor case 30. Further, asupport hole 30 a is formed in a position on the peripheral upper edgeof the sensor case 30 so as to correspond to and to rotatively receivethe case support section 36 of the hanger 38.

While being attached to the retractor base 1, the case support section36 of the hanger 38 serves as a pivot axis extending in parallel withthe seat reclining pivot 71 of the backrest 62 of the reclining vehicleseat 61.

Accordingly, while being attached to the retractor base 1 by way of thehanger 38, the sensor case 30 is supported by the retractor base 1 so asto be pivotable about a pivot axis S extending in parallel with the seatreclining pivot 71 of the backrest 62.

The inertial body support surface 30 b of the sensor case 30 is formedinto the shape of a fan having its center extending below the mainportion of the fan. The bottom center in which the inertial body supportsurface 30 b is formed is connected to a joint section 51 which has anelongated hole 50 to be joined to a rotation transmission means 39,which will be described later.

The inertial body 33 assumes a spherical shape and is placed on theinertial body support surface 30 b. Upon receipt of a velocity change ofgreater than a predetermined level, the inertial body 33 moves inrelation to the inertial body support surface 30 b, thereby movingtoward the first position the sensor arm 31 brought into contact withthe exterior surface of the inertial body 33. The radius of the inertialbody 33 is set so that the center of the inertial body 33 is located atthe pivot axis S of the sensor case 30 when the inertial body 33 isplaced at the center of the inertial body support surface 30 b. When theinertial body 33 is placed in the center of the inertial body supportsurface 20 b, the sensor arm 31 is retained in the second position evenwhen the sensor case 30 is rotated about the pivot axis S.

The transmission means 39 pivots the sensor case 30 about the pivot axisS thereof in synchronization with the reclining action of the backrest62 according to the reclining angle thereof such that the inertial bodysupport surface 30 b is retained in an appropriate orientationregardless of reclining angle of the backrest 62. The sensor case 30joined to the transmission means 39 is not pivoted about the pivot axisS by the inertial force which would otherwise be exerted on the sensorcase 30 in the event of collision.

As shown in FIG. 1, the transmission means 39 comprises a slide member53 which is disposed in the seat portion 63 of the reclining seat 61 soas to be linearly movable forward and backward; a cam plate 54 which ispivoted about the seat reclining pivot 71 and which causes the slidemember 53 to advance or recede within only a predetermined rangecorresponding to the optimum working range of the seat belt according tothe reclining action of the backrest 62; and a wire 56, one end of whichis connected to the slide member 53 and the other end of which isconnected to the joint section 51 of the sensor case 30 and which servesas a transmission member for transmitting the movement of the slidemember 53 to the sensor case 30. The wire 56, which is a flexibletransmission member, is inserted into a flexible guide tube 55, one endof which is fixed, by way of a fixed portion 55 a, to the vicinity ofthe position where the slide member 53 is provided and the other end ofwhich is connected to the retractor base 1 provided in the backrest 62.

The slide member 53 comprises a contact receiver 53 a which is freelymoved forward and backward along a guide frame 58 mounted on the seatportion 63, and an operation pin 53 b which is provided integrally withthe contact receiver 53 a and is inserted in an elongated hole 58 a ofthe guide frame 58. As shown in FIG. 1, a press element 57 provided atone end of the wire 56 is brought into contact with the contact receiver53 a, and an operation section 65 of the cam plate 54 engages theoperation pin 53 b.

The cam plate 54 is supported so as to be pivotal about the seatreclining pivot 71 and comprises an elongated hole 67 which is engagedby a fixed pin 66 mounted on the backrest 62 in an upright position, andthe hook-shaped operation section 65 that engages the operation pin 53b. The elongated hole 67 extends in a circular arc shape centered on theseat reclining pivot 71. When the backrest 62 is in a reclined positionbeyond the most-backwardly reclined position within the working range ofthe seat belt (as shown in FIG. 4), the fixed pin 66 is arranged so asto come into contact with the front end of the elongated hole 67 (i.e.,the left end of the elongated hole 67 shown in FIG. 1).

A compressed coil spring 73 is sandwiched between the rear end of theelongated hole 67 (i.e., the right end of the elongated hole 67 shown inFIG. 1) and the fixed pin 66. When the backrest 62 is reclined back, thecam plate 54 is pivoted clockwise in FIG. 1 about the seat recliningpivot 71, by way of the fixed pin 66 and the compressed coil spring 73,in association with the rearward reclining action of the backrest 62.Since the compressed coil spring 73 possesses a sufficient spring force,the pivotal movement of the cam plate 54 is continued with the fixed pin66 in contact with the front end of the elongated hole 67 until thebackrest 62 is reclined back to the maximum reclined position within theoptimum working range of the seat belt, as shown in FIG. 4.

When an attempt is made to backwardly recline the backrest 62 beyond themaximum reclined position (i.e., so as to exceed the optimum workingrange of the seat belt), the operation pin 53 b reaches the front end ofthe elongated hole 58 a of the guide frame 58 (the left end of theelongated hole 58 a shown in FIG. 6), thereby hindering the pivotalmovement of the cam plate 54 engaging the operation pin 53 b. As aresult, as shown in FIG. 6, the fixed pin 66 advances toward the backend of the elongated hole 67 while compressing the compressed coilspring 73, so that only the backrest 62 is pivoted but the cam plate 54remains stationary.

Specifically, when the backrest 62 is reclined back within the optimumworking range of the seat belt, the cam plate 54 is pivoted in aclockwise direction in FIG. 1, thereby pressing the slide member 53 in aleftward direction in FIG. 1 by way of the operation pin 53 b engagingthe operation section 65. However, when the backrest 62 is reclined backbeyond the optimum working range of the seat belt, the pivotal movementof the cam plate 54 is hindered, thereby preventing pressing of theslide member 53 in the leftward direction in FIG. 1 in response to thereclining action of the backrest 62. Thus, the cam plate 54 constitutesa synchronous movement cancelation mechanism.

When the backrest 62 is raised gradually from the reclined positionoutside the optimum working range of the seat belt shown in FIG. 6, thecompressed coil spring 73 is restored to its original state inassociation with the raising action of the backrest 62. When thebackrest 62 reaches the maximum reclined position within the optimumworking range of the seat belt, the fixed pin 66 comes into contact withthe front end of the elongated hole 67, as shown in FIG. 4. If thebackrest 62 is raised further, the cam plate 54 is pivoted in acounterclockwise direction in FIG. 1 in association with the forwardreclining action of the backrest 62, so that the operation section 65recedes in a rightward direction in FIG. 1.

When the backrest 62 is further reclined forward after having passedthrough the maximum forward reclined position (shown in FIG. 1) withinthe optimum working range of the seat belt, the operation pin 53 breaches the back end of the elongated hole 58 a of the guide frame 58(i.e., the right end of the elongated hole 58 a shown in FIG. 7),thereby hindering the movement of the slide member 53 in the rightwarddirection in FIG. 1. As shown in FIG. 7, the operation section 65 of thecam plate 54 is disengaged from the operation pin 53 b of the slidemember 53, thus bringing the cam plate 54 into a synchronous movementcancelation state in which the operation section 65 does not affect theforward and backward movement of the slide member 53.

An operating element 59 provided at the end of the wire 56 facing theretractor base 1 is supported by a guide member 77 mounted on theretractor base 1 so as to be able to move back and forth and isconnected to the sensor case 30 by way of a pin 59 a inserted into theelongated hole 50 formed in the joint section 51 of the sensor case 30.By means of a compressed coil spring 76 interposed between the operatingelement 59 and the guide member 77, the press element 57 is constantlyurged so as to remain in contact with the contact section 53 a of theslide member 53. The compressed coil spring 76 is set so as to have aforce weaker than that of the compressed coil spring 73, and thereforethe compressed coil spring 76 will not press and displace the slidemember 53 engaging the cam plate 54.

In accordance with the reclining action of the backrest 62, the camplate 54 moves the slide member 53 forward and backward within only thelongitudinal range of the elongated hole 58 a of the guide frame 58corresponding to the optimum working range of the seat belt. Accordingto the reclining angle of the backrest 62, the transmission means 39pivots the sensor case 30 about its pivot axis S in synchronization withthe reclining action of the backrest 62 by way of the wire 56 thattransmits the movement of the slide member 53, in such a way as to holdthe inertial body support surface 30 b in an appropriate orientationregardless of reclining angle of the backrest 62.

When the backrest 62 is reclined, the inertial body support surface 30 bof the sensor case 30 of the vehicle body acceleration sensor 32according to the first embodiment is retained in an appropriate positionby means of the transmission means 39 that operates in synchronizationwith the reclining action of the backrest 62. Therefore, even when thereclined position of the backrest 62 is changed, the sensor case 30 isretained in an appropriate position. Hence, only the inertial body 33placed on the sensor case 30 is moved by the inertial force which wouldbe caused by physical shock in the event of an emergency. Therefore, thesensitivity of the sensor is prevented from becoming deteriorated,thereby enabling the sensor to reliably and stably sense theacceleration of the vehicle body.

Further, the transmission means 39 of the vehicle body accelerationsensor 32 has the foregoing synchronous movement cancelation mechanism.If the backrest 62 is reclined beyond the pivotable range of the sensorcase 30 (i.e., the working angle range of the vehicle body accelerationsensor 32), the transmission means 39 cancels the movement of the sensorcase 30 that is synchronous with the reclining action of the backrest62. Here, in order to prevent damage to the sensor case 30, thepivotable range of the sensor case 30 is set so as to become slightlywider than the reclining range of the backrest 62 within the optimumworking range of the seat belt.

As shown in FIGS. 6 and 7, even when the backrest 62 is reclined beyondthe working angle range of the vehicle body acceleration sensor 32, thereclining force of the backrest 62 is prevented from acting on thesensor case 30 by way of the wire 56, thus preventing strain on thesensor case 30. Accordingly, the provision of the transmission means 39does not cause such inconvenience as to limit the reclining angle of thebackrest 62. Further, the sensor case 30 is prevented from pivoting morethan necessary, thereby preventing the seat belt retractor 100 frombecoming bulky.

Further, the transmission means 39 that retains the inertial bodysupport surface 30 b in an appropriate position in synchronization withthe reclining action of the backrest 62 is made up of a simple mechanismsuch as that formed from the slide member 53, the cam plate 54, and thewire 56 and does not require an expensive component such as a motor.Accordingly, manufacturing costs can also be prevented from increasing.

FIG. 9 is a schematic side view showing a reclining seat, in which aseat belt retractor 200 equipped with a vehicle body acceleration sensor232 according to a second embodiment of the present invention isincorporated in the backrest. The components which are the same as thoseused in the seat belt retractor 100 according to the first embodimentare assigned the same reference numerals, and repetition of theirdetailed explanations is omitted.

As in the case with the seat belt retractor 100 according to the firstembodiment shown in FIG. 1, the seat belt retractor 200 is built intothe backrest 62 of the reclining seat 61 mounted on the vehicle body.

The reclining (tilting) range of the backrest 62 extends from aforwardly reclined state A shown in FIG. 9 to the maximum backwardlyreclined state D, i.e., a fully flat state, in which the surface of thebackrest 62 is substantially level with the surface of the seat portion63. The reclined state of the backrest 62 suitable for the occupantduring driving ranges from a reclined state B in which the backrest 62is slightly reclined back from its upright position to a reclined stateC in which the backrest 62 is reclined back to an appropriate extent.The reclining range from the reclined state B to the reclined state C isan optimum working range E of the seat belt in which the seat belt iscapable of correctly restraining the occupant.

Although not shown in detail, the seat belt retractor 200 comprises thetake-up shaft 4 which is fitted into a substantially cylindrical bobbin,around which the webbing 70 is wound, and which is rotatably supportedby a retractor base 223, and the emergency lock mechanism 300 that, inthe event of an emergency, prevents rotation of the take-up shaft 4 inthe direction in which the webbing 70 is drawn-out. The webbing 70extending from the retractor 200 by way of the slot 64 formed in thebackrest 62 restrains the occupant.

The retractor base 223 mounted on a frame member (not shown) of thebackrest 62 is formed from a metal plate through press molding such thatthe majority of the retractor base 223 assumes a substantially angularC-shaped cross section. The take-up shaft 4 fitted into the bobbin isrotatable and is sandwiched between the sides plates 223 a and 223 b ofthe retractor base 223. The end of the take-up shaft 4 that passesthrough the side plate 223 b of the retractor base 223 is provided witha known take-up spring device (not shown). At all times, the take-upspring device urges the bobbin, in the direction in which the webbing 70is taken up, by way of the take-up shaft 4.

The vehicle body acceleration sensor 232 according to the secondembodiment is provided below the ratchet wheel 19 constituting theemergency lock mechanism 300.

As shown in FIGS. 10 and 11, the vehicle body acceleration sensor 232according to the second embodiment comprises a sensor arm 231, a sensorcase 236, an inertial body 233, a case support member 237, atransmission means 239, and a synchronous movement cancelation mechanism238.

The sensor case 236 comprises an inertial body support surface 236 a onwhich the inertial body 233 is placed, and an arm support section 236 bthat rotatively supports the sensor arm 231. The inertial body supportsurface 236 a of the sensor case 236 is formed into the shape of a fanhaving its center extending below the main portion of the fan.

The case support member 237 comprises a case support section 240 inwhich the sensor case 236 is removably fitted; a pivot section 241 whichextends upward from one side of the case support section 240 and isrotatably supported so as to rotate around the pivot axis T of thetake-up shaft 4; and a tongue-shaped joint section 242 extending fromthe pivot section 241 in a radially outward direction.

The joint section 242 is connected to transmission means 239, which willbe described later. When the backrest 62 is reclined, the case supportmember 237 is pivoted by the transmission means 239 in synchronizationwith the reclining action of the backrest 62. The pivot section 241 issupported so as to be able to pivot about the pivot axis T of thetake-up shaft 4 by way of, for example, a bearing bush of the retractorbase whose mount through holes are positioned in the vicinity of theouter periphery of the take-up shaft 4.

A pin section provided at the base end of the sensor arm 231 isrotatively supported by the sensor case 236. While the sensor case 236is attached to the retractor, the sensor arm 231 can be pivoted aboutthe pin section provided at the base end thereof and can switch betweena first position—where a leading edge 231 b of the sensor arm 231engages the teeth 19 a of the ratchet wheel 19—and a second positionwhere the leading edge 231 b is disengaged from the teeth 19 a. In thefirst position, there is actuated a lock means of the retractor whichprevents rotation of the take-up shaft 4 in the direction in which thewebbing is drawn-out. In the second position, the lock means is notactuated. A dish-shaped contact section 231 c which is in contact withan upper portion of the inertial body 233 in order to detect themovement of the inertial body 244 is integrally formed with the sensorarm 241.

The “lock means” used herein signifies the emergency lock mechanism 300from which the vehicle body acceleration sensor 232 is excluded.

The inertial body 233 assumes a spherical shape and is placed on theinertial body support surface 236 a. Upon receipt of a velocity changegreater than a predetermined magnitude, the inertial body 233 moves inrelation to the inertial body support surface 236 a, thereby moving tothe first position the sensor arm 231 that remains in contact with theoutside of the inertial body 233.

When the leading edge 231 b of the sensor arm 231 engages the teeth 19 aof the ratchet wheel 19, the ratchet wheel 19 rotates so as to lagbehind the take-up shaft 4. As a result, the pole 11 engages the latchplate 4 a by way of the latch cup 13, thereby bringing the lock meansinto an operative state. Consequently, there is prevented rotation ofthe take-up shaft 4 in the direction in which the webbing is drawn-out.

The transmission means 239 pivots the sensor case 236 about its pivotaxis according to the reclining angle of the backrest 62 in such a wayas to retain the inertial body support surface 236 a in an appropriateorientation regardless of reclining angle of the backrest 62. The sensorcase 236 joined to the transmission means 239 is prevented from pivotingabout the pivot axis by the inertial force which would be exerted in theevent of collision.

As shown in FIGS. 10 and 11, the transmission means 239 comprises apress plate 250 fixed on the seat portion 63; a wire 246 which serves asa transmission member and is pressed and actuated by a folded presspiece 250 a formed on the press plate 250 to thereby pivot the sensorcase 236 about its pivotable axis within only a predetermined rangecorresponding to the optimum working range of the seat belt insynchronization with the reclining action of the backrest; and a guidetube 245 which houses the wire 246 in a slidable fashion and is providedin the backrest 62.

As shown in FIG. 10, a guide member 252 fixed on the side plate 223 a ofthe retractor base 223 is attached to the retractor-side end section 245a of the guide tube 245—in which the wire 246 is inserted—in such a waythat a slider 251 connected to one end of a coil spring 249—the otherend of which is connected to a retractor-side end section 246 a of thewire 246—passes by an area in the vicinity of the joint section 242 ofthe case support member 237. The retractor-side end section 246 a of thewire 246 is joined to the case support member 237 by way of the slider251 on which a joint pin 251 a to be engaged with an elongated hole 242a of the joint section 242 is formed in an upright position, therebyconstituting a retractor-side joint section.

As shown in FIG. 11, a reclining-pivot-side end section 245 b of theguide tube 245 is mounted on a fixed plate 272 attached to the backrest62, by way of a guide member 248 in such a way that a follower 247joined to a reclining-pivot-side end 246 b of the wire 246 extends tothe press piece 250 a of the press plate 250. The press piece 250 a ofthe press plate 250 attached to the seat portion 63 imparts to thefollower 247 displacement corresponding to the reclining angle of thebackrest 62 within the optimum working range of the seat belt.

A reclining-pivot-side end section 248 a of the guide member 248 ismounted on the fixed plate 272 of the backrest 62 so as to become spaceda given distance apart from the seat reclining pivot 71. The follower247 connected to the reclining-pivot-side end section 246 b of the wire246 is urged by means of an unillustrated spring member in a directionof arrow (N) so as to protrude from the open end of thereclining-pivot-side end section 248 a of the guide member 248 by agiven length L₁ toward the seat reclining pivot 71. When the backrest 62is reclined, the reclining-pivot-side end section 248 a of the guidemember 248 moves along a circular-arc R—which is spaced a given radiusaway from the seat reclining pivot 71—in conjunction with the backrest62.

When the backrest 62 is in a reclined state B which is shown in FIG. 9and is the start position of the optimum working range E of the seatbelt, the guide member 248 and the follower 247 are placed in positionB₁ shown in FIG. 11 with respect to the press piece 250 a of the pressplate 250, in which the follower 247 starts coming into contact with thepress piece 250 a.

Similarly, when the backrest 62 is in a reclined state C which is shownin FIG. 9 and is the end position of the optimum working range E of theseat belt, the guide member 248 and the follower 247 are placed inposition C₁ shown in FIG. 12, in which the follower 247 is pushed intothe press piece 250 a in association with the reclining action of thebackrest 62. As a result, the length of a projected portion of thefollower 247 is diminished to L₂.

The wire 246—whose retractor-side end section 246 a is connected to thecase support member 237 by way of the slider 251—pivots the case supportmember 237 in a direction of arrow (M) shown in FIG. 10 by only theextent to which the press piece 250 a—which constitutes thereclining-pivot-side joint section together with the follower247—presses the follower 247 toward the retractor, thereby regulatingthe angle of the sensor case 236.

When the backrest 62 is reclined forward from the start position of theoptimum working range E of the seat belt, the seat belt is not used andhence the angular adjustment of the sensor case 236 is not required. Asshown in FIG. 13, the front end of the follower 247 departs from theforegoing press piece 250 a, and the follower 247 retains its initialprojection length L₁ and does not adjust the orientation of the sensorcase 236.

Accordingly, when the backrest 62 is in a reclined state at any locationbetween the start position and the end position of the optimum workingrange E of the seat belt, the leading end of the follower 247 protrudingtoward the seat reclining pivot 71 comes into contact with the presspiece 250 a of the press plate 250, thereby displacing the wire 246 inits axial direction according to the reclining angle of the backrest 62.The wire 246 actuated by the press piece 250 a pivots the case supportmember 237 about the pivot axis T of the take-up shaft 4—which is alsothe pivotable axis of the case support member 237—by way of the slider251, thereby controlling the orientation of the inertial body supportsurface 236 a of the sensor case 236.

When the backrest 62 is reclined back further in a backward directionfrom the reclined position C, the guide member 248 and the follower 247are placed in position C₂ shown in FIG. 14. In response to the backwardreclining action of the backrest 62, the follower 247 is further pushedby the press piece 245 a, so that the length of projection of thefollower 247 toward the seat reclining pivot 71 is diminished to L₃.

In this way, when the backrest 62 is reclined beyond the backwardreclining limit of the optimum working range E of the seat belt, theleading end of the slider 251 comes into contact with a guide groove end252 a of the guide member 252, as shown in FIGS. 15 and 16, therebypreventing further displacement of the slider 251.

When the backrest 62 exceeds the backward reclining limit of the optimumworking range E of the seat belt, the displacement exerted on the wire246 by the press piece 250 a is absorbed by the deflection of the coilspring 249 interposed between the slider 251 and the retractor-side endsection 246 a serving as a retractor-side joint section of the wire 246.Specifically, the coil spring 249 has such a spring strength as not tobe changed in its inherent length even when subjected to frictionalresistance of the slider 251 which is slid within the guide groove ofthe guide member 252 as a result of displacement of the wire 146.

In the synchronous movement cancelation mechanism 238 of the vehiclebody acceleration sensor 232 according to the second embodiment, whenthe backrest 62 is reclined forward beyond the optimum working range Eof the seat belt, the follower 247 that serves as thereclining-pivot-side joint section of the wire 246 departs from thepress piece 250 a, thereby canceling the movement of the sensor case 236which is synchronous with the reclining action of the backrest 62.Further, when the backrest 62 is reclined back beyond the optimumworking range E of the seat belt, the coil spring 249 is compressed,thereby absorbing the displacement of the wire 246. As a result, themovement of the sensor case 236 that is synchronous with the recliningaction of the backrest 62 is canceled.

In the vehicle body acceleration sensor 232, when the backrest 62 of thereclining seat 61 is reclined beyond the optimum working range E of theseat belt, the synchronous movement cancelation mechanism 238 cancelsthe operation of the transmission means 239 which regulates theorientation of the inertial body support surface 236 a of the sensorcase 236 in synchronization with the reclining action of the backrest62.

As mentioned above, when the backrest 62 is reclined beyond the optimumworking range E of the seat belt, the sensor case 236 is not pivoted insynchronization with the reclining action of the backrest 62.Accordingly, the space for movement of the sensor case 236 does not haveto be made larger than necessary, thereby rendering the retractor 200compact.

The pivotable range of the sensor case 236 is limited by the synchronousmovement cancelation mechanism 238 canceling the angular adjustment ofthe sensor case 236 by the transmission means 239. The transmissionmeans 239 does not limit the reclining angle of the backrest 62 per se.The reclining seat 61 according to the present invention does notdiminish the reclining seat when compared with a seat not having abuilt-in retractor. Consequently, the reclining seat 61 does not becomedifficult to use as a vehicle seat.

FIGS. 17 through 20 show a seat belt retractor 201 equipped with avehicle body acceleration sensor 321 according to a third embodiment ofthe present invention. In all respects other than those addressed below,the retractor 201 equipped with the vehicle body acceleration sensor 321is substantially identical in structure with the seat belt retractor 200according to the second embodiment, and hence repetition of theirdetailed explanations is omitted.

In the vehicle body acceleration sensor 321 according to the thirdembodiment, a sensor case 361 having an inertial body support surface361 a for supporting the inertial body 233 is supported so as to be ableto pivot about a pivotable axis 321 a, by a case support member 371mounted on a side plate 233 a of the retractor base 223. The pivotableaxis 321 a is set so as to pass through the center of the inertial body233. The sensor arm 231 engages the ratchet wheel 19 in association withthe movement of the inertial body 233 placed on the inertial bodysupport surface 361 a of the sensor case 361, thereby actuating the lockmechanism 300. The sensor arm 231 is supported so as to be able to pivotabout a pivot axis 371 a of the case support member 371.

As shown in FIGS. 18 through 20, transmission means 391 for regulatingthe tilt angle of the sensor case 361 according to the reclining angleof the backrest 62 comprises a flexible shaft 331 which serves as atransmission member and is actuated torsionally in accordance with thereclining action of the backrest 62; a guide tube 332 in which theflexile shaft 331 is inserted so as to be torsionally rotatable; astationary bevel gear 334 which is fixed on the seat portion 63 suchthat the axis of the stationary bevel gear 334 matches the seatpivotable axis 71 of the backrest 62; a drive bevel gear 333 which isconnected to the end of the flexible shaft 331 facing the seat recliningpivot 71 and meshes with the stationary bevel gear 334; a worm wheel 331which serves as a gear having a cam and is rotated by means of thetorsional rotation of the flexible shaft 331 while meshing with a wormgear 331 a formed on the retractor-side end portion of the flexibleshaft 331; and a cam groove 335 which is formed in the worm wheel 311and serves as a cam for pivoting the sensor case 361 in association withthe rotation of the worm wheel 311.

In the transmission means 391, when the backrest 62 is reclined, theflexible shaft 331 is torsionally actuated by means of the drive bevelgear 333 that rotates in conjunction with the stationary bevel gear 334,and the worm wheel 311 is rotated in accordance with the amount oftorsional movement of the flexible shaft 331. When the worm wheel 311 isrotated, the sensor case 361 is pivoted so as to follow the cam groove335 formed in the worm wheel 311. Specifically, the torsional rotationof the flexible shaft 331 is transmitted to the sensor case 361 by wayof an engagement arm 361 b. As shown in FIG. 19, an engagementprotuberance 361 c which follows the cam groove 335 of the worm wheel311 is formed at the leading edge of the engagement arm 361 b.

As shown in FIG. 20, in order to pivot the sensor case 361 insynchronization with the reclining action of the backrest 62, the camgroove 335 of the worm wheel 311 comprises three cam profiles; namely, afirst cam groove 335 a extending from a start point F to an intermediatepoint G; a second cam groove 335 b extending from the intermediate pointG to another intermediate point H; and a third cam groove 335 cextending from the intermediate point H to an end point I.

The first cam groove 335 a corresponds to the reclining action of thebackrest 62 within the range from the reclined state A to the reclinedstate B shown in FIG. 9. The second cam groove 335 b corresponds to thereclining action of the backrest 62 within the range from the reclinedstate B to the reclined state C shown in FIG. 9. The third cam groove335 c corresponds to the reclining action of the backrest 62 from thereclined state C to the reclined state D shown in FIG. 9.

More specifically, the second cam groove 335 b corresponds to thereclining action of the backrest 62 within the optimum working range Eof the seat belt. The second cam groove 335 b assumes a cam profilewhich gradually departs from a rotational center 336 of the worm wheel311 in such a way that the sensor case 361 pivots in association withthe rotation of the worm wheel 311. The first and third cam grooves 335a and 335 c correspond to the reclining action of the backrest 62outside the optimum working range E of the seat belt. Each of the twocam grooves 335 a and 335 c is formed into a circular arc which isspaced a given distance away from the rotational center 336 so as toprevent the sensor case 361 from pivoting in synchronization with thebackrest 62.

Accordingly, in the transmission means 391 according to the thirdembodiment, when the backrest 62 is reclined beyond the optimum workingrange E of the seat belt, the first and third cam grooves 335 a and 335c formed in the worm wheel 311 prevent the sensor case 361 from pivotingin synchronization with the reclining action of the backrest 62. Thus,in the vehicle body acceleration sensor 321 according to the thirdembodiment, the worm wheel 311 having the cam groove 335 formed thereinacts as a synchronous movement cancelation mechanism 338 which preventsthe sensor case 361 from pivoting in synchronization with the recliningaction of the backrest 62.

In the vehicle body acceleration sensor 321 according to the thirdembodiment, the synchronous movement cancelation mechanism 338 isinterposed between the sensor case 361 and the worm gear 331 a thatserves as the retractor-side joint section of the flexible shaft 331.Accordingly, there can be avoided a mechanism which is provided in linewith the seat reclining pivot 71 of the backrest 62 and which transmitsthe reclining action of the backrest 62 to the reclining-pivot-sidejoint section of the flexible shaft 331. Therefore, in addition to theoperation and working effect yielded by the vehicle body accelerationsensor 232 according to the second embodiment, the vehicle bodyacceleration sensor 321 according to the third embodiment yields anadvantage of the ability to cope with a plurality of types of seats byminor modification of the retractor.

FIGS. 21 through 23 show a seat belt retractor 400 equipped with avehicle body acceleration sensor 422 according to a fourth embodiment ofthe present invention. The vehicle body acceleration sensor 422according to the fourth embodiment is identical with in configurationthe vehicle body acceleration sensor 321 according to the thirdembodiment, except for the configuration of a worm wheel 412 oftransmission means 492 for controlling the tilt angle of the sensor case361 in synchronization with the reclining action of the backrest 62.Hence, detailed descriptions of the other elements are omitted.

In transmission means 492 according to the fourth embodiment, the wormwheel 412—serving as a gear with a cam—has a cam groove 411 which servesas a cam for pivoting the sensor case 361 in association with therotation of the worm wheel 412 and which differs from the cam groove 335according to the third embodiment.

As shown in FIG. 22, the cam groove 422 comprises four cam profiles:namely, a first cam groove 422 a extending from a starting point F to anintermediate point G; a second cam groove 422 b extending from theintermediate point G to another intermediate point H; a third cam grove422 c extending from the intermediate point H to still anotherintermediate point; and a fourth cam groove 422 d extending from theintermediate point J to an end point I.

The first cam groove 422 a corresponds to the reclining action of thebackrest 62 within the range from the reclined state A to the reclinedstate B shown in FIG. 9. The second cam groove 422 b corresponds to thereclining action of the backrest 62 within the range from the reclinedstate B to the reclined state C shown in FIG. 9. The third cam groove422 c corresponds to the reclining action of the backrest 62 within aconsiderable narrow range beyond the reclined state C shown in FIG. 9.The fourth cam groove 422 d corresponds to the reclining action of thebackrest 62 within the range from the reclined state C to the reclinedstate D shown in FIG. 9.

More specifically, the second cam groove 422 b corresponds to thereclining action of the backrest 62 within the optimum working range Eof the seat belt. The second cam groove 442 b assumes a cam profilewhich gradually departs from a rotational center 336 of the worm wheel412 in such a way that the sensor case 361 pivots in association withthe rotation of the worm wheel 412. The first and fourth cam grooves 422a and 422 d correspond to the reclining action of the backrest 62outside the optimum working range E of the seat belt. Either of the twocam grooves 422 a and 422 d is formed into a circular arc which isspaced a given distance away from the rotational center 336 so as toprevent the sensor case 361 from pivoting in synchronization with thebackrest 62. Thus, the worm wheel 412 acts as a synchronous movementcancelation mechanism 439 which prevents the sensor case 361 frompivoting in synchronization with the reclining action of the backrest62.

As shown in FIG. 23, when the backrest 62 is reclined beyond thebackward reclining limit of the optimum working range E of the seatbelt, the third cam groove 422 c tilts the sensor case 361 to a tiltangle of the inertial body support surface 361 a, thereby moving theinertial body 233. As a result, the sensor arm 231 engages the teeth 19a of the ratchet wheel 19.

More specifically, in the transmission means 429 according to the fourthembodiment, when the backrest 62 is reclined beyond the backwardreclining limit of the optimum working range E of the seat belt, thesensor case 361 is pivoted a great amount by means of the third camgroove 422 c, so that the emergency lock mechanism 300 is actuated tothereby hinder withdrawal of the webbing.

The inertial body support surface 361 a of the sensor case 361 is formedinto the shape of a fan having its center extending below the mainportion of the fan. Even if the backrest 62 is reclined beyond theoptimum working range E of the seat belt, the inertial body 233 is notimmediately moved until the sensor case 361 is tilted to or beyond thetilt angle of the inertial body support surface 361 a. If no third camgroove 422 c is provided, the webbing 70 may not be locked immediatelyeven when the backrest 62 is reclined to the backward reclining limit ofthe optimum working range E of the seat belt.

The inclination of the vehicle body, or the like, affects and changesthe angle through which the backrest 62 is actually reclined from whenangular adjustment of the sensor case 361 is interrupted as a result ofthe backrest 62 reaching the backward reclining limit of the optimumworking range E of the seat belt until the sensor case 361 is tilted toor beyond the tilt angle of the inertial body support surface 361 a.

Therefore, there exists a vague gray zone in which it is not clearwhether or not withdrawal of the webbing 70 is prevented. When thebackrest 62 is in the reclined position within the gray zone, the seatbelt may be erroneously fastened.

According to the fourth embodiment, if the backrest 62 is reclined tothe backward reclining limit of the optimum working range E of the seatbelt, the third cam groove 422 c immediately tilts the sensor case 361to or beyond the tilt angle of the inertial body support surface 361 a,thereby actuating the emergency lock mechanism 300 and eliminating theforegoing gray zone. As a result, when the backrest 62 is backwardlyreclined beyond the optimum working range E of the seat belt, thewithdrawal of the webbing is reliably prevented, thus preventingfastening of the seat belt.

FIG. 24 is a schematic side view showing a reclining seat, in which aseat belt retractor 500 equipped with a vehicle body acceleration sensor532 according to a fifth embodiment of the present invention isincorporated in the backrest. Those components which are the same asthose used in the seat belt retractor 200 according to the secondembodiment are assigned the same reference numerals, and repetition oftheir detailed explanations are omitted.

As shown in FIGS. 25 and 26, the seat belt retractor 500 comprises asubstantially cylindrical bobbin 2 around which the webbing 70 is wound;a take-up shaft 4 which is inserted into the bobbin 2, is rotativelysupported by means of a retractor base 501, and has at one end thereof(i.e., on the right-hand side of the take-up shaft 4 shown in FIG. 26)the latch plate 4 a formed from a ratchet wheel; and the emergency lockmechanism 300 which, in the event of an emergency, prevents rotation ofthe latch plate 4 a in a direction in which the webbing 70 is drawn-out.The webbing 70 withdrawn from the retractor 500 by way of a slot 64formed in the backrest 62 restraints the occupant.

The retractor base 501 mounted on a frame member (not shown) of thebackrest 62 is formed from a metal plate through press molding such thatthe majority of the retractor base 501 assumes a substantially angularC-shaped cross section. The take-up shaft 4 fitted into the bobbin 2 isrotatable and sandwiched between both sides plates 501 a and 501 b ofthe retractor base 501. The end of the take-up shaft 4 that passesthrough the side plate 501 b of the retractor base 1 is provided with aknown take-up spring device (not shown). At all times, the take-upspring device urges the bobbin 2 in the direction in which the webbing70 is taken up, by way of the take-up shaft 4.

In the seat belt retractor 500, the vehicle body acceleration sensor 532according to the fifth embodiment is provided below the ratchet wheel 19that constitutes the emergency lock mechanism 300.

As shown in FIGS. 25 and 26, the vehicle body acceleration sensor 532comprises a sensor arm 531, a sensor case 530, an inertial body 533, andtransmission means 539.

The sensor case 530 comprises a case body 536 having an inertial bodysupport surface 536 a on which the inertial body 533 is placed, and ahanger member 537 extending upward from one side surface of the casebody 536. The upper end of the hanger member 537 is supported in arotatable manner by a bearing bush 538 which supports the take-up shaft4. More specifically, the pivot axis T of the sensor case 530 is in linewith the rotational axis of the take-up shaft 4 that extends in parallelwith the seat reclining pivot 71.

The inertial body support surface 536 a of the case body 536 is formedinto the shape of a fan having its center extending below the mainportion of the fan. The case body 536 is removably attached at apredetermined location of the hanger member 537. Further, atongue-shaped joint section 537 b is formed so as to extend in aradially outward direction in a ring section of the hanger member 537supported by the bearing bush 538, and an elongated hole 537 a engagedwith transmission means 539, which will be described later, is formed inthe joint section 537 b.

A pin section 531 a provided at the base end of the sensor arm 531 isrotatively supported. While the sensor case 530 is attached to theretractor, the sensor arm 531 can be pivoted about the pin section 531 athereof and can switch between a first position—where a leading edge 531b of the sensor arm 531 engages the teeth 19 a of the ratchet wheel 19to thereby prevent the take-up shaft 4 from rotating in the direction inwhich the webbing is drawn-out—and a second position—where the leadingedge 531 b is disengaged from the teeth 19 a to thereby preventactuation of the lock means.

When the leading edge 531 b of the sensor arm 531 engages the teeth 19 aof the ratchet wheel 19, the ratchet wheel 19 rotates so as to lagbehind the take-up shaft 4. As a result, the pole 11 engages the latchplate 4 a by way of the latch cup 13, thereby preventing rotation of thetake-up shaft 4 in the direction in which the webbing is drawn-out.

The inertial body 533 assumes a spherical shape and is placed on theinertial body support surface 536 a. Upon receipt of a velocity changegreater than a predetermined magnitude, the inertial body 533 moves inrelation to the inertial body support surface 536 a, thereby moving tothe first position the sensor arm 531 that remains in contact with theoutside of the inertial body 533.

The transmission means 539 pivots the sensor case 530 about its pivotaxis T according to the reclining angle of the backrest 62 in such a wayas to retain the inertial body support surface 536 a in an appropriateorientation regardless of reclining angle of the backrest 62. The sensorcase 530 joined to the transmission means 539 is prevented from pivotingabout the pivot axis T by the inertial force which would be exerted inthe event of collision.

The transmission means 539 comprises a cam plate 554 having a camsurface extending in the peripheral direction from the seat recliningpivot 71; a rod member 551 which serves as a transmission member,follows the cam surface of the cam plate 554, and pivots the sensor case530 about the pivot axis within only the pivotable range of the sensorcase 530 in synchronization with the reclining action of the backrest;and a guide tube 552 which houses the rod member 551 in a slidablefashion.

In place of the rod member 551 according to the fifth embodiment, theremay be employed a wire which possesses appropriate flexibility forbending so as to fit a location where the wire is laid, such as theinside of the backrest 62, such that one end of the wire is connected toa follower that is joined to a side edge of the cam plate and isprovided so as to be able to move back and forth toward the cam surfaceof the cam plate. The other end of the wire is joined to the sensorcase, and the wire possesses appropriate strength for moving along theinside of the guide tube without buckling when receiving a longitudinalforce.

As shown in FIG. 25, a retractor-side end section 552 b of the guidetube 552 in which the rod member 551 is inserted is mounted on a sideplate 501 a of the retractor base 501 so that a retractor-side endsection 551 b of the rod member 551 passes through the vicinity of ajoint section 537 b of the hanger member 537. As shown in FIG. 27, acam-plate-side end section 552 a of a guide tube 552 is fixedlypositioned on a support plate 556 fixed to the backrest 62 such that thecam-plate-side end section 551 a of the rod member 551 protrudes towardthe seat reclining pivot 71 of the backrest 62 (i.e., the cam-plate-sideend section 551 a of the rod member 551 is placed on a line U passingthrough the seat reclining pivot 71 of the backrest 62).

One end of the retractor-side end section 551 b of the rod member 551 isconnected to the hanger member 537 by way of a pin 555 which engages anelongated hole 537 a of the joint section 537 b. Further, theretractor-side end section 551 b is urged toward the other end thereofby means of an unillustrated compressed coil spring provided in theguide member 557 attached to the retractor-side end section 552 b of theguide tube 552. The cam-plate-side end section 551 a of the rod member551 serves as a follower which follows the cam surface of the cam plate554, and is urged so as to remain in contact with the cam surface of thecam plate 554 by a restoration force of the compressed coil springprovided within the guide member 557.

The outer surface of the cam plate 554 mounted on the seat portion 63serves as a cam surface. When the backrest 62 is reclined, thecam-plate-side end section 551 a of the rod member 551 moves back andforth along the line U.

The cam surface of the cam plate 554 comprises three cam surfaceportions: namely, a synchronous movement cam surface portion 554 a whichserves as a synchronous movement region, in which the sensor case 530 ispivoted about its pivot axis T according to the reclining angle of thebackrest 62; and cam surface portions 554 b and 554 c which continuefrom respective sides of the cam surface portion 554 a and serve asnon-synchronous movement regions, in which the sensor case 530 is notpivoted in synchronization with the reclining action of the backrest 62.

When the backrest 62 is reclined within the optimum working range of theseat belt in which the webbing 70 can appropriately restrain anoccupant, the synchronous movement cam surface portion 554 a controlsthe forward and backward movement of the cam-plate-side end section 551a of the rod member 551 in such a way that the inertial body supportsurface 536 a of the case body 536 is retained in an appropriateorientation regardless of reclining angle of the backrest 62.

When the backrest 62 is in the maximum forwardly-reclined state (shownin FIG. 24) within the optimum working range of the seat belt, thecam-plate-side end section 551 a of the rod member 551 is positioned ata portion of the synchronous movement cam surface portion 554 a close tothe non-synchronous movement cam surface portion 224 b, as shown in FIG.27. When the backrest 62 is backwardly reclined from this state, thecam-plate-side end section 551 a of the rod member 551 moves in aclockwise direction in FIG. 27 about the seat reclining pivot 71 inconjunction with the reclining action of the backrest 62. Thecam-plate-side end section 551 a is pushed by the synchronous movementcam surface portion 554 a. The rod member 551 that is pushed by thesynchronous movement cam surface portion 554 a when the backrest 62 isbackwardly reclined pivots the hanger member 537 attached to the casebody 536 about the take-up shaft 4 in a counterclockwise direction inFIG. 25, thereby retaining the inertial body support surface 536 a ofthe case body 536 in an appropriate orientation.

When the backrest 62 is in the maximum backwardly-reclined state (shownin FIG. 28) within the optimum working range of the seat belt, thecam-plate-side end section 551 a of the rod member 551 is positioned ata portion of the synchronous movement cam surface portion 554 a close tothe non-synchronous movement cam surface portion 554 c, as shown in FIG.30, whereby the hanger member 537 attached to the case body 536 retainsthe inertial body support surface 536 a of the case body 536 in anappropriate orientation, as shown in FIG. 29.

Accordingly, when the backrest 62 is reclined within the range from thereclined position shown in FIG. 24 to the reclined position shown inFIG. 28, the seat belt apparatus can appropriately restrain the occupantby use of the webbing 70. In short, the range corresponds to an optimumworking range of the retractor 500.

As shown in FIG. 27, the length J₁ and curvature of the synchronousmovement cam surface portion 554 a are set so as to correspond to theoptimum working range of the seat belt. The range in which the hangermember 537 is pivoted by means of the synchronous movement cam surfaceportion 554 a by way of the rod member 551 corresponds to the pivotablerange of the sensor case 530 (i.e., an operative angular range of thevehicle body acceleration sensor 532). Here, the pivotable range of thesensor case 530 is set so as to become slightly wider than the recliningrange of the backrest 62 within the optimum working range of the seatbelt, so as to prevent damage to the sensor case 530.

When the backrest 62 is reclined beyond the optimum working range of theretractor 500 in which the webbing 70 cannot appropriately restrain theoccupant, the non-synchronous movement cam surface 554 b or 554 c limitthe forward and backward movement of the cam-plate-side end section 551a of the rod member 551, thus serving as a synchronous movementcancelation mechanism for preventing the sensor case 530 from pivotingin synchronization with the backrest 62.

The non-synchronous movement cam surface portion 554 b is intended tolimit the forward and backward movement of the cam-plate-side endsection 551 a of the rod member 551 when the backrest 62 is reclinedbeyond the maximum forwardly reclined state (shown in FIG. 24) withinthe optimum working range of the seat belt. Hence, the non-synchronouscam surface portion 554 b continues from one side of the synchronousmovement cam surface portion 554 a, as shown in FIG. 27.

The non-synchronous movement cam surface portion 554 c is intended tolimit the forward and backward movement of the cam-plate-side endsection 551 a of the rod member 551 when the backrest 62 is reclinedbeyond the maximum backwardly reclined state (shown in FIG. 28) withinthe optimum working range of the seat belt. Hence, the non-synchronousmovement cam surface portion 554 c continues from the other end of thesynchronous movement cam surface portion 554 a.

These non-synchronous movement cam surfaces 554 b and 554 c are formedinto circular-arc shapes centered on the seat reclining pivot 71. Thehanger member 537 is prevented from being actuated in synchronizationwith the reclining action of the backrest by maintaining constant theinterval between the seat reclining pivot 71 of the backrest 62 and thecam-plate-side end section 551 a of the rod member 551.

FIG. 31 shows the reclined state of the backrest 62 when the backrest 62is reclined beyond the reclined state shown in FIG. 24; FIG. 32 showsthe pivoted state of the hanger member 537; and FIG. 33 shows theposition of the cam-plate-side end section 551 a on the non-synchronousmovement cam surface portion 554 b. Even when there is a change in thereclined state of the backrest 62, the pivoting state of the hangermember 537 remains unchanged and the cam-plate-side end section 551 aremains in contact with a portion of the synchronous movement camsurface portion 554 a close to the non-synchronous movement cam surfaceportion 554 b.

FIG. 34 shows the reclined state of the backrest 62 when the backrest 62is reclined beyond the reclined state shown in FIG. 28; FIG. 35 showsthe pivoted state of the hanger member 537; and FIG. 36 shows theposition of the cam-plate-side end section 551 a on the non-synchronousmovement cam surface portion 554 c. Even when there is a change in thereclined state of the backrest 62, the pivoting state of the hangermember 537 remains unchanged and the cam-plate-side end section 551 aremains in contact with the portion of the synchronous movement camsurface portion 554 a close to the non-synchronous movement cam surfaceportion 554 c.

The length J₂ of the non-synchronous cam surface portion 554 b and thelength J₃ of the non-synchronous cam surface portion 554 c are set so asto correspond to the required reclining angle of the backrest 62.

As mentioned above, in the vehicle body acceleration sensor 532according to the fifth embodiment, so long as the backrest 62 isreclined within the optimum working range of the seat belt (i.e., arange which is slightly narrower than the pivotable range of the sensorcase 530), the rod member 551 of the transmission means 539 follows thesynchronous movement cam surface portion 554 a, thereby pivoting thesensor case 530 in synchronization with the reclining action of thebackrest 62. Consequently, the inertial body support surface 536 a isretained in an appropriate orientation.

Therefore, even when the reclined position of the backrest 62 ischanged, the sensor case 530 is retained in an appropriate position.Hence, the inertial body 533 placed on the sensor case 30 is moved bythe inertial force which would arise from physical shock in the event ofan emergency. Therefore, the sensitivity of the sensor is prevented frombecoming deteriorated, thereby enabling the sensor to reliably andstably sense the acceleration of the vehicle body.

Further, even if the backrest 62 is reclined beyond the optimum workingrange of the seat belt, the rod member 551 follows the non-synchronousmovement cam surface portions 554 b and 554 c, thereby canceling themovement of the sensor case 530 that is synchronous with the recliningaction of the backrest 62. Hence, there does not arise suchinconvenience as to limit the reclining angle of the backrest 62 withinthe pivotable range of the sensor case 530. Further, there is no need toensure a large space for movement of the sensor case 530 in order toincrease the pivotable range thereof in accordance with the recliningangle of the backrest, as would have been practiced conventionally,thereby preventing the retractor 500 from becoming bulky.

While the backrest 62 is held in a backwardly reclined position beyondthe optimum working range of the seat belt, the sensor case 530 isbrought into a canceled state, in which the sensor case 530 does notpivot in synchronization with the reclining action of the backrest 62.Therefore, the seat belt retractor 500 causes the pole 11 to engage thelatch plate 4 a, thereby preventing rotation of the take-up shaft 4 inthe direction in which the webbing 70 is withdrawn. Therefore, when thebackrest 62 is held in a backwardly reclined state beyond the optimumworking range of the seat belt, there is prevented withdrawal of theseat belt, which is likely to result in a so-called submarine phenomenonin which the body of the occupant squeezes through the space below thewebbing in the event of collision and bursts out in a forward direction.

The transmission means 539 that retains the inertial body supportsurface 536 a in an appropriate orientation in synchronization with thereclining action of the backrest 62 is made up of a simple mechanismsuch as that formed from the rod member 551 of simple shape, and the camplate 54 which can be inexpensively and simply mass-produced by pressworking of a plate material and does not require an expensive component,such as a motor. Accordingly, manufacturing costs can be prevented fromincreasing.

By provision of cam plates having different cam profiles, there may beproduced a vehicle body acceleration sensor of superior versatilitywhich can be used with a plurality of types of reclining seats and seatbelt retractors through selection of an appropriate one of the camplates.

In the fifth embodiment, the cam-plate-side end section 551 a of the rodmember 551 that serves as a transmission member is fixed in the backrest62 by means of the support plate 556 mounted on the backrest 62.Alternatively, there my be used a flexible transmission member such as awire. In this case, a follower joined to the cam-plate-side end sectionof the wire may be fixed on the seat portion 63 so as to be able to moveback and forth toward the cam surface of the cam plate. Since the wireis bent every time the backrest 62 is reclined, the wire must havesufficient durability.

In the fifth embodiment, the cam-plate-side end section 551 a of the rodmember 551 is fixedly positioned so as to protrude toward the seatreclining pivot 71 of the backrest 62. If there is made a contrivance tothe cam profile of the cam surface formed on the cam plate 554, thedirection in which the cam-plate-side end section 551 a protrudes may bechanged.

So long as the cam-plate-side end section 551 a of the rod member 551 isfixedly positioned in such a manner as previously described withreference to the fifth embodiment, the transmission means 539 thatpivots the sensor case 530 about its pivot axis T according to thereclining angle of the backrest 62 may render the cam profile of the camplate 554 comparatively simple and facilitate positional adjustment ofthe cam plate 554 and the rod member 551.

FIG. 37 is a schematic side view showing a reclining seat, in which aseat belt retractor 600 equipped with a vehicle body acceleration sensor632 according to a sixth embodiment of the present invention isincorporated into the backrest. Those components which are the same asthose used in the seat belt retractor 500 having the vehicle bodyacceleration sensor 532 according to the fifth embodiment are assignedthe same reference numerals, and repetition of their explanations isomitted.

Although not shown in detail, the seat belt retractor 600 comprises asubstantially cylindrical take-up shaft around which the webbing 70 iswound and which is rotatably supported by a retractor base 601; and anemergency lock mechanism 301 which, in the event of an emergency,prevents rotation of the take-up shaft in the direction in which thewebbing is drawn-out. More specifically, as shown in FIG. 38, theemergency lock mechanism 301 is slightly different in structure from theemergency lock mechanism 300. A ratchet wheel 619—which serves as lockactivation means—rotates so as to lag behind the take-up shaft, therebycausing a pole (not shown) which is supported as lock means at one endof the take-up shaft to engage a section-to-be-engaged of the retractorbase 601. Accordingly, rotation of the take-up shaft in the direction inwhich the webbing is drawn-out is prevented.

The vehicle body acceleration sensor 632 according to the sixthembodiment is provided below the ratchet wheel 619 and comprises thesensor arm 531, the sensor case 530, the inertial body 533, andtransmission means 639.

The transmission means 639 comprises a cam plate 654 which is fixed tothe seat portion 63 and has a cam surface extending in the peripheraldirection from the seat reclining pivot 71; a follower 660 which isfixed in the area of the backrest 62 in the vicinity of the cam plate654 so as to be able to move back and forth toward the cam surface ofthe cam plate 654 and which has a rack 660 a formed thereon andextending in the direction in which the follower 660 moves back andforth; a pinion gear 670 which is provided so as to be able to mesh withthe rack 660 a of the follower 660 and to rotate; a wire 651 which has acam-plate-side end section 651 a joined to the pinion gear 670 and aretractor-side end section 651 b joined to the sensor case 530 through ajoint member 655 and which transmits the rotation of the pinion gear 670to the sensor case 530; and a guide tube 652 housing the wire 651.

The joint member 655 is connected to a feed screw 671 joined to theretractor-side end section 651 b of the wire 651 through screwengagement and moves along the feed screw 671 in accordance with theamount of torsional rotation of the wire 651. Further, the joint member655 is joined to the hanger member 537 by way of a lock pin 655 a whichengages the elongated hole 537 a of the joint section 537 b.

The follower 660 is fitted, in a slidable manner, into a cylindricalmember 661 fixed on the backrest 62 and is urged so as to remain incontact with the cam surface of the cam plate 654 by a restoration forceof a compressed coil spring 662 provided within the cylindrical member661. The cylindrical member 661 is mounted on the backrest 62 at aposition a given distance away from the seat reclining pivot 71. Asshown in FIG. 39, when the backrest 62 is reclined, the cylindricalmember 661 travels over a circular arc R₁ spaced a given radial distanceaway from the seat reclining pivot 71, together with the backrest 62. InFIG. 39, a position A of the cylindrical member 661 corresponds to thebackrest 62 when it is forwardly reclined as shown in FIG. 31.Similarly, a position B of the cylindrical member 661 corresponds to thebackrest 62 when it is reclined to the start position of the optimumworking range of the seat belt, as shown in FIG. 24. Similarly, aposition C of the cylindrical member 661 corresponds to the backrest 62when it is reclined to the end position of the optimum working range ofthe seat belt, as shown in FIG. 28. Similarly, a position D of thecylindrical member 661 corresponds to the backrest 62 when it isforwardly reclined as shown in FIG. 34.

The follower 660 is urged by means of the compressed coil spring 662 soas to protrude from an open end of the cylindrical member 661 by a givenlength X₁ toward the seat reclining pivot 71.

The cam plate 654 comprises an angle adjustment cam surface 654 a whichimparts displacement to the follower 660 when the backrest 62 isreclined within the optimum working range of the seat belt; and a limitcam surface 654 b which hinders displacement of the follower 660 whenthe backrest 62 is reclined backward beyond the optimum working range ofthe seat belt.

When the backrest 62 is reclined within the optimum working range of theseat belt from its start to end positions, the leading edge of thefollower 660 comes into contact with the angle adjustment cam surface654 a. The angle adjustment cam surface 654 a is formed into such aprofile as to displace the follower 660 in its axial direction accordingto the reclining angle of the backrest 62. When the angle adjustment camsurface 654 a imparts displacement to the follower 660, the pinion gear670 meshing with the rack 660 a of the follower 660 is rotated. The wire651 whose cam-plate-side-end section 651 a is joined to the pinion gear670 is torsionally actuated, thereby displacing the joint member 655 ina longitudinal direction by an amount corresponding to the amount oftorsional movement of the wire 651. As a result, the sensor case 530 ispivoted.

Accordingly, the vehicle body acceleration sensor 632 according to thesixth embodiment yields the same operations and working effects as thoseyielded by the vehicle body acceleration sensor 532 according to thefifth embodiment. The vehicle body acceleration sensor can sense theacceleration of the vehicle body stably without fail. There can beprovided an inexpensive vehicle body acceleration sensor for use with aseat belt which does not raise such inconvenience as to limit thereclining angle of the backrest 62 within the pivotable range of thesensor case 530.

As shown in FIG. 40, the follower 660 according to the sixth embodimentis fixedly positioned so as not to extend toward the seat recliningpivot 71 of the backrest 62 (that is, as indicated by an imaginary linein the drawing, the center axis of the cylindrical member 661 is notdisposed on a line U which passes through the seat reclining pivot 71 ofthe backrest 62), as well as to raise in an upright direction.

More specifically, a cam contact portion of thespherically-or-cylindrically formed follower 660 which comes intocontact with the cam receives a force P from the cam surface. This forceP corresponds to a force in the direction normal to the cam surface andcan be divided into a component force P_(Y1) acting in the direction inwhich the follower 660 moves and a component force P_(Y2) acting in adirection perpendicular to the direction of movement of the follower660. As designated by the phantom line shown in FIG. 40, if the follower660 protrudes toward the seat reclining pivot 71, the force P exerted onthe leading edge of the follower 660 can be divided into a componentforce P_(Y2) acting in the direction in which the follower 660 moves anda component force P_(X2) acting in a direction perpendicular to thedirection of movement of the follower 660.

In a case where the follower 660 is arranged so as to protrude towardthe seat reclining pivot 71, the component force P_(X2) acting in thedirection perpendicular to the direction of movement of the follower 660becomes great, and may twist or strain the follower 660, which is fittedinto the cylindrical member 661 in a slidable manner.

Accordingly, the direction in which the follower 660 advances or recedesis preferably set such that the cam contact portion of the follower 660which advances or recedes in the direction toward the cam surfaceimparts an optimum pressing force to the entire area of the cam surfacewith which the cam contact section makes slidable contact (i.e., theangle adjustment cam surface 654 a and the limit cam surface 654 b).

FIG. 41 is a schematic side view showing a reclining seat, in which aseat belt retractor 700 equipped with a vehicle body acceleration sensor732 according to a seventh embodiment of the present invention isincorporated into the backrest.

As shown in FIGS. 42 and 43A, the seat belt retractor 700 comprises thesubstantially cylindrical bobbin 2 around which the webbing 70 is wound;the take-up shaft 4 which is inserted into the bobbin 2, is rotativelysupported by means of a retractor base 701, and has at one end thereof(i.e., on the right-hand side of the take-up shaft 4 shown in FIG. 42)the latch plate 4 a formed from a ratchet wheel; and the emergency lockmechanism 300, all of which are identical to those described with thepreceding embodiments. The webbing 70 withdrawn from the retractor 700by way of a slot (not shown) formed in the backrest 62 restraints theoccupant.

The retractor base 701 mounted on a frame member (not shown) of thebackrest 62 is formed from a metal plate through press molding such thatthe majority of the retractor base 1 assumes a substantially angularC-shaped cross section. The take-up shaft 4 fitted into the bobbin 2 isrotatable and sandwiched between both sides plates 701 a and 701 b ofthe retractor base 701. The end of the take-up shaft 4 that passesthrough the side plate 701 b of the retractor base 701 is provided witha known take-up spring device (not shown). At all times, the take-upspring device urges the bobbin 2 in the direction in which the webbing70 is taken up, by way of the take-up shaft 4.

In the seat belt retractor 700, the vehicle body acceleration sensor 732according to the seventh embodiment is provided below the ratchet wheel19 that constitutes the emergency lock mechanism 300.

As shown in FIGS. 42, 43A, and 43B, the vehicle body acceleration sensor732 comprises a sensor arm 731, a sensor case 736, an inertial body 733,a case support member 737, and transmission means 739.

The sensor case 736 comprises an inertial body support surface 736 a onwhich the inertial body 733 is placed, and an arm support member 736 bwhich supports the sensor arm 731 in a rotatable manner. The inertialbody support surface 736 a of the case body 736 is formed into the shapeof a fan having its center extending below the main portion of the fan.As shown in FIGS. 43A and 43B, the case support member 737 comprises acase support section 740 into which the sensor case 736 is removablyfitted; a pivot support section 741 which extends upward from one sidesurface of the case support section 740 and is supported by theretractor base 701 in a rotatable manner; and a joint section 742 joinedto transmission means 739 to be described later. Further, a take-upsurface 744 continues from the joint section 742 and is positionedconcentrically and in line with the take-up shaft 4.

The pivot support section 741 of the case support member 737 issupported so as to be able to pivot about the pivot axis T of thetake-up shaft 4. When the backrest 62 is reclined, the transmissionmeans 739 joined to the joint section 742 pivots the case support member737 in synchronization with the reclining action of the backrest 62,thereby adjusting the sensor case 736 to an appropriate orientation byway of the case support member 737.

As shown in FIGS. 42 and 43A, a pin section 731 a provided at the baseend of the sensor arm 731 is rotatively supported by the sensor case736. While the sensor case 736 is attached to the retractor 701, thesensor arm 731 can be pivoted about the pin section 731 a thereof andcan switch between a first position—where a leading edge 731 b engagesthe teeth 19 a of the ratchet wheel 19 to thereby prevent the take-upshaft 4 from rotating in the direction in which the webbing isdrawn-out—and a second position—where the leading edge 731 b isdisengaged from the teeth 19 a to thereby prevent actuation of the lockmeans.

When the leading edge 731 b of the sensor arm 731 engages the teeth 19 aof the ratchet wheel 19, the ratchet wheel 19 rotates so as to lagbehind the take-up shaft 4. As a result, the pole 11 engages the latchplate 4 a by way of the latch cup 13, thereby preventing rotation of thetake-up shaft 4 in the direction in which the webbing is drawn-out.

The inertial body 733 is placed on the inertial body support surface 736a. Upon receipt of a velocity change greater than a predeterminedmagnitude, the inertial body 733 moves in relation to the inertial bodysupport surface 736 a, thereby moving to the first position the sensorarm 731 that remains in contact with the outside of the inertial body733.

The transmission means 739 pivots the sensor case 736 about its pivotaxis T according to the reclining angle of the backrest 62 in such a wayas to retain the inertial body support surface 736 a in an appropriateorientation regardless of the reclining angle of the backrest 62. Thesensor case 736 joined to the transmission means 739 by way of the casesupport member 737 is prevented from pivoting about the pivot axis T bythe inertial force which would be exerted in the event of collision.

As shown in FIGS. 43A and 43B, the transmission means 739 comprises acam plate 780 which is fixed on the seat portion 63 and has an innerperipheral cam surface 782 extending in a circumferential directionabout the seat reclining pivot 71; a follower 790 (not labeled in FIGS.43A and 43B) provided so as to be able to advance or recede along theinner peripheral cam surface 782 of the cam plate 780; an inner cable792 which has a cam-plate-side end section connected to the follower 790and a retractor-side end section joined to the sensor case 736 by way ofthe case support member 737 and which transmits the forward and backwardmovement of the follower 790 to the sensor case 736; an outer tube 794housing the inner cable 792 in a slidable manner; and a spring 789 whichis formed from a compressed coil spring serving as an urging member andis capable of urging the follower 790 toward the inner peripheral camsurface 782 by way of the inner cable 792. Although in the seventhembodiment the flexible inner cable 792 is used as transmission means,there may also be used a rod member capable of transmitting the advanceor receding movement of the follower to the sensor case.

As shown in FIG. 43A, a retractor-side end section 794 b of the outertube 794 in which the inner cable 792 is inserted is mounted on a sideplate 701 a of the retractor base 701. As shown in FIG. 43B, acam-plate-side end section 794 a of the outer tube 794 is fixed on anarm 783—which is pivotable about the seat reclining pivot 71 inassociation with the backrest 62—such that the follower 790, which willbe described later, is able to move back and forth along the innerperipheral cam surface 782 of the cam plate 780.

As shown in FIGS. 44 and 45, the arm 783 has a pair of arm plates 784,784 for holding the cam plate 780 therebetween. A guide groove 784 a isformed in each of the arm plates 784, 784 for guiding a roller holder796 of the follower 790, which will be described later, in a slidablemanner.

One end of the retractor-side end section of the inner cable 792 isconnected to the joint section 742 of the case support member 737 by wayof the terminal member 792 of the inner cable 792 and is moved along thetake-up surface 744 concentric with the take-up shaft 4. Further, aspring 789 to be interposed between the retractor-side end section 794 band the joint section 742 is wrapped around the retractor-side endsection of the inner cable 792.

As shown in FIGS. 44 and 45, the follower 790 joined to thecam-plate-side end section of the inner cable 792 comprises the rollerholder 796 that is joined to the cam-plate-side end section of the innercable 792 and is slidably guided along the guide grooves 784 a, 784 a;and a roller 795 which is rotatably supported on the roller holder 796by the support pin 798 and is rotatable over the inner peripheral camsurface 782 of the cam plate 780. The roller holder 796 attached to thearm 783 is prevented from becoming dislodged from the guide grooves 784a by means of washers 797 having a diameter greater than the width ofthe guide groove 784 a.

The follower 790 is constantly urged toward the retractor by therestoration force of the spring 789 by way of the inner cable 792,thereby enabling urging of the roller 795 toward the inner peripheralcam surface 782.

In the seventh embodiment, the outer surface of the slit 781 extendingfrom the center of the seat reclining pivot 71 from the forwarddirection of the seat in the circumferential direction also serves asthe inner peripheral cam surface 782 which causes the follower 790 tomove back and forth along the guide grooves 784 a of the arms 783 whenthe backrest 62 is reclined. The roller 795 of the follower 790 engageswith only the outer surface of the slit 781, i.e., the inner peripheralcam surface 782, and hence the inner surface of the slit 781 is notrequired to be formed in parallel with the outer surface of the same.For this reason, the inner peripheral cam surface formed in the camplate can also be realized by means of an opening having a desired innerperipheral cam surface.

The inner peripheral cam surface 782 of the cam plate 780 has only asynchronous movement area, wherein the sensor case 736 is pivoted aboutthe pivot axis T according to the reclining angle of the back rest 62 insynchronization with the reclining action thereof, within only the rangeof the backrest in which the occupant can use the seat.

When the backrest 62 is reclined from the most forwardly reclinedposition to the most backwardly reclined position (i.e., a full-flatstate) within the range in which the occupant can use the seat, theinner peripheral cam surface 782 controls the forward and backwardmovement of the follower 790 by way of the inner cable 792 such that theinertial body support surface 736 a is held in an appropriateorientation regardless of the reclining angle of the backrest 62.

When the backrest 62 is in the most forwardly reclined position withinthe range in which the occupant can use the seat (i.e., the positionshown in FIG. 41), the follower 790 is situated at an opening end of theslit 781 which serves as the front end of the inner peripheral camsurface 782, as shown in FIG. 43B. In this position, the base end of theroller 796 is in contact with the upper ends 785 of the guide grooves784 a, and the spring 789 is in a compressed state.

When the backrest 62 is reclined backward from this position, the arm783 pivots about the seat reclining pivot 71 in a counterclockwisedirection in FIG. 43B together with the backrest 62 in accordance withthe reclining angle of the backrest 62.

The roller holder 796 of the follower 790 is pressed down along theinner peripheral cam surface 782 by way of the roller 795. The innercable 792 joined to the roller holder 796 that is pressed down along theinner peripheral cam surface 782 when the backrest 62 is reclinedbackward is withdrawn in the direction of arrow W shown in FIG. 43Bagainst the restoration force of the spring 789. The inner cable 792whose other end is connected to the joint section 742 of the casesupport member 737 pivots, about the take-up shaft 4, the case supportmember 737 attached to the sensor case 736 in a clockwise directionshown in FIG. 43A, thereby retaining the inertial body support surface736 a of the sensor case 736 in an appropriate orientation.

The cam profile of the inner peripheral cam surface 782 is set such thatthe follower 790 slides over a given distance downwardly according tothe reclining angle of the backrest 62 and that the inner cable 792 iswithdrawn in the direction of arrow W by an amount corresponding to thereclining angle of the backrest 62. Further, the retractor-side endsection of the inner cable 792 that is withdrawn in the direction ofarrow W is wrapped around the take-up surface 744 of the case supportmember 737. Hence, the case support member 737 is pivoted through apredetermined angle corresponding to the distance over which the innercable 792 is moved. Accordingly, the sensor case 736 attached to thecase support member 737 is pivoted through an angle corresponding to thereclining angle of the backrest 62.

For this reason, even if the reclining angle of the backrest 62 ischanged, the sensor case 736 is retained in an appropriate orientation,and the inertial body 733 placed on the sensor case 736 is moved only bythe inertial force which would arise from physical shock in the event ofan emergency. Therefore, the sensitivity of the sensor is prevented frombecoming deteriorated, thereby enabling the sensor to reliably andstably sense the acceleration of the vehicle body.

Until, as shown in FIG. 46, the backrest 62 is reclined to the mostbackwardly reclined position (i.e., a full-flat state), the follower 790follows the inner peripheral cam surface 782, as shown in FIG. 47B, andis moved in such a direction as to approach the seat reclining pivot 71along the guide groove 784 a of the arm 783. The inner cable 792 iswithdrawn in the direction of arrow W by means of the follower 790. Thesensor case 736 is pivoted in a clockwise direction about the pivot axisT by an amount corresponding to the distance of movement of the innercase 792, by way of the case support member 737 and against therestoration force of the spring 789, as shown in FIG. 47A.

In contrast, the follower 790 follows the inner peripheral cam surface782 and is moved in such a direction as to depart from the seatreclining pivot 71 along the guide grooves 784 a of the arm 783, and theinner cable 792 on which the restoration force of the spring 789 isexerted is withdrawn in the direction opposite to the direction of arrowW. The sensor case 736 is pivoted in a counterclockwise direction aboutthe pivot axis T by an amount corresponding to the distance of movementof the inner case 792, by way of the case support member 737.

The length and profile of the inner peripheral cam surface 782 aredetermined so as to correspond to the working range of the retractor700. The range over which the case support member 737 is pivoted by theinner peripheral cam surface 782 by way of the follower 790 correspondsto the pivotable range of the sensor case 736. Here, the pivotable rangeof the sensor case 736 is set so as to be slightly wider than thereclining range of the backrest 62 within the optimum working range ofthe seat belt, so as to prevent damage to the sensor case 736.

As shown in FIG. 48, the backrest 62 may be reclined beyond the range inwhich the occupant can use the seat from the position shown in FIG. 41.As a result, as shown in FIG. 49B, the follower 790 is disengaged fromthe slit 781, and the roller 795 becomes disengaged from the innerperipheral cam surface 782. Since the base end of the roller 796 comesinto contact with the upper ends 785 of the guide grooves 784 a, and thefollower 790 does not travel along the guide grooves 784 a of the arms783. Accordingly, the inner cable 792 remains stationary and does notproject or recede. By means of a tapered portion 781 a formed in theopening section of the slit 781, the roller 795 of the follower 790 canenter the slit 781 without fail.

Within a range in which the occupant cannot use the seat, the innercable 792 neither projects nor becomes withdrawn, there is no change ina relative position between the sensor case 736 and the retractor 700,as shown in FIG. 49A. As a result, the sensor case 736 is brought into asynchronous movement cancelation state in which the sensor case 736 isnot pivoted in synchronization with the reclining action of the backrest62.

Therefore, the reclining angle of the backrest 62 is prevented frombeing limited by the pivotable range of the sensor case 736. Further,the sensor case 736 is prevented from being unnecessarily rotated insynchronization with the reclining action of the backrest 62, therebypreventing the retractor 700 from becoming bulky.

The transmission means 739 that retains the inertial body supportsurface 736 a in an appropriate orientation in synchronization with thereclining action of the backrest 62 is made up of a simple mechanismsuch as that formed from the follower 790 and the inner cable 792, bothof which have simple configurations, and the cam plate 780 which can beinexpensively and simply mass-produced by press working of a platematerial, and does not require an expensive component, such as a motor.Accordingly, manufacturing costs can be prevented from increasing.

By provision of cam plates having different cam profiles, there may beproduced a vehicle body acceleration sensor of superior versatilitywhich can be used with a plurality of types of reclining seats and seatbelt retractors through selection of an appropriate one of the camplates.

FIGS. 50 and 51 show a modification of the cam plate according to theseventh embodiment.

An inner peripheral cam surface 712 formed along the outer surface of aslit 711 of a cam plate 710 comprises an inner peripheral cam surface712 a for synchronous movement purpose in which the sensor case 736 ispivoted only within the optimum working range of the seat belt insynchronization with the reclining action of the backrest 62, and aninner peripheral cam surface 712 b for non-synchronous movement purposein which the sensor case 736 is not pivoted in synchronization with thereclining action of the backrest 62.

When the backrest 62 is reclined within the range in which the occupantcan use the seat as well as within the optimum working range of theretractor 700 in which the occupant can be appropriately restrained bymeans of the webbing 70, the inner peripheral cam surface 712 a controlsthe forward and backward movement of the follower 790 such that theinertial body support surface 736 a of the sensor case 736 is retainedin an appropriate orientation (i.e., in an upright direction) regardlessof reclining angle of the backrest 62. As in the case with the innerperipheral cam surface 782, the inner peripheral cam surface 712 aassumes a curved cam profile which gradually approaches the seatreclining pivot 71 in response to the reclining action of the backrest62.

In contrast, when the backrest 62 is reclined within the range in whichthe occupant can use the seat as well as beyond the optimum workingrange of the retractor 700 in which the occupant cannot be appropriatelyrestrained by means of the webbing 70, the inner peripheral cam surface712 b acts as a synchronous movement cancelation mechanism whichcontrols the forward and backward movement of the follower 790 tothereby prevent the sensor case 736 from pivoting in synchronizationwith the reclining action of the backrest 62. To this end, the innerperipheral cam surface 712 b assumes a circular-arc cam profile centeredon the seat reclining pivot 71 and prevents the case support member 737from pivoting in synchronization with the reclining action of thebackrest 62, by maintaining a constant distance between the seatreclining pivot 71 of the backrest 62 and the follower 790.

When the backrest 62 is reclined backward beyond the optimum workingrange of the seat belt, the sensor case 736 is brought into a canceledstate in which the sensor case 736 is not pivoted in synchronizationwith the reclining action of the backrest 62. As a result, the inertialbody support surface 736 a is tilted in conjunction with the backrest62, thereby actuating the lock means of the emergency lock mechanism300. The emergency lock mechanism 300 causes the pole 11 to engage withthe latch plate 4 a, thereby preventing rotation, in the direction inwhich the webbing is drawn-out, of the take-up shaft 4, thus hinderingwithdrawal of the webbing 70.

An inner peripheral cam surface 722 formed on the outer surface of theslit 721 of the cam plate 720 comprises an inner peripheral cam surface722 a for synchronous movement purpose in which the sensor case 736 ispivoted only within the optimum working range of the seat belt insynchronization with the reclining action of the backrest 62; an innerperipheral cam surface 722 b for non-synchronous movement purpose inwhich the sensor case 736 is not pivoted in synchronization with thereclining action of the backrest 62; and an inner peripheral cam surface722 c for forceful actuation purpose which is formed between the innerperipheral cam surface 722 a and the inner peripheral cam surface 722 band which serves as a forceful actuation region in which the inertialbody 733 is moved by pivoting the sensor case 736 by an angle greaterthan the reclining angle of the inertial body support surface 736 a.

As in the case with the inner peripheral cam surface 721 a forsynchronous movement purpose of the cam plate 710, the inner peripheralcam surface 722 a for synchronous movement purpose controls the forwardand backward movement of the follower 790 such that the inertial bodysupport surface 736 a is retained in an appropriate orientationregardless of reclining angle of the backrest 62, and hence assumes acam profile equal to that of the inner peripheral cam surface 721 a forsynchronous movement purpose. As in the case with the inner peripheralcam surface 712 b for non-synchronous movement purpose of the cam plate710, the inner peripheral cam surface 722 b for non-synchronous movementpurpose acts as a synchronous movement cancelation mechanism whichprevents the sensor case 736 from pivoting in synchronization with thereclining action of the backrest 62, and hence assumes a cam profileequal to that of the inner peripheral cam surface 721 b fornon-synchronous movement purpose.

When the backrest 62 is reclined beyond the backward limit angle of theoptimum working range of the seat belt, the inner peripheral cam surface722 c for forceful actuation purpose controls the forward and backwardmovement of the follower 790 such that the sensor case 736 is tilted atan angle sufficiently greater than the reclining angle of the inertialbody support surface 736 a, thereby forcefully moving the inertial body733. The inner peripheral cam surface 722 c assumes a linear cam profilewhich departs from the seat reclining pivot 71 according to the backwardreclining action of the backrest 62.

More specifically, when the reclining angle of the backrest 62 exceedsthe backward limit angle of the optimum working range of the seat belt,the follower 790 which follows the inner peripheral cam surface 722 cpivots the sensor case 736 to a great extent, thereby activating theemergency lock mechanism 300 and preventing withdrawal of the webbing70.

The inertial body support surface 736 a of the sensor case 736 is formedinto the shape of a fan having its center extending below the mainportion of the fan. By virtue of the shape of the inertial body supportsurface 736 a, even when the backrest 62 is reclined beyond the optimumworking range of the seat belt, the inertial body 733 does not moveuntil the sensor case 736 pivots to an angle greater than the recliningangle of the inertial body support surface 736 a. In a case where thereis no inner peripheral cam surface 722 c for forceful actuation purpose,the withdrawal of the webbing 70 may not be locked immediately even whenthe backrest 62 is reclined to the backward limit angle of the optimumworking range of the seat belt.

More specifically, the inclination of the vehicle body or the likeaffects and changes the angle through which the backrest 62 is actuallyreclined, from the time when angular adjustment of the sensor case 736is interrupted as a result of the backrest 62 reaching the backwardreclining limit of the optimum working range of the seat belt until thetime the sensor case 736 is tilted to or beyond the tilt angle of theinertial body support surface 736 a.

Therefore, there exists a vague gray zone in which it is not clearwhether or not withdrawal of the webbing 70 is prevented. When thebackrest 62 is in the reclined position within the gray zone, the seatbelt may be erroneously fastened.

In the vehicle body acceleration sensor for seat belt employing the camplate 720, even if the backrest 62 is reclined to the backward reclininglimit of the optimum working range of the seat belt, the innerperipheral cam surface 722 c for forceful actuation purpose immediatelytilts the sensor case 736 to or beyond the tilt angle of the inertialbody support surface 736 a, thereby actuating the emergency lockmechanism 300 and eliminating the foregoing gray zone. As a result, whenthe backrest 62 is backwardly reclined beyond the optimum working rangeof the seat belt, withdrawal of the webbing is reliably prevented, thuspreventing fastening of the seat belt.

FIG. 52 is a schematic perspective view showing a reclining seat havinga seat belt retractor 800 which is equipped with a vehicle bodyacceleration sensor 832 according to an eighth embodiment of the presentinvention.

The seat belt retractor 800 is built into the backrest 62 of thereclining seat 61 mounted on a vehicle body. The backrest 62 isconnected to the seat portion 63 so as to be pivotal about a seatreclining pivot extending in the widthwise direction of the vehiclebody. The inclination of the backrest 62 is adjusted according to thephysique of an occupant. A take-up member 880 is disposed in line withthe seat reclining pivot by way of a first plate 897 to be describedlater with reference to FIG. 54.

FIG. 53 is an exploded perspective view showing the take-up member 880.As shown in FIG. 53, the take-up member 880 constituting transmissionmeans 890 comprises a case 881 fixed to a first plate 897 to bedescribed later; a fan-shaped slider 882 around which is wrapped a innercable 892 serving as a transmission member of the transmission means890; a lever 883 which limits pivotal movement of the slider 882 bymeans of a protuberance 832 b and has a cylindrical section 883 aserving as a pivot of the slider 882; a washer 884; a nut 885 capable offastening the lever 883 to a bolt 898 b of a second plate 898 to bedescribed later, by way of the washer 884; and a cover 886 to beattached to the case 881.

The take-up member 880 constitutes angle sensing means for sensing thereclining angle of the backrest 62 by detection of a relative rotationbetween the case 881 which is disposed on the backrest and pivotstogether with the backrest 62 and the slider 882 which is disposed onthe seat portion.

The case 881 comprises a mount hole 881 a which permits fastening of thecase 881 to the first plate 897 through use of a bolt (not shown); ahole 881 b which permits insertion of the cylindrical portion 883 a ofthe lever 883; a groove 881 c for receiving a large diametrical portion893 of an outer tube 894 in which the inner cable 892 is inserted; apassageway 881 d which is in communication with the groove 881 c andreceives the inner cable 892 inserted into the outer tube 894; and a rib881 e for limiting pivotal movement of the slider 882.

The slider 882 comprises a cylindrical portion 882 a which is fittedaround the cylindrical portion 883 a of the lever 883 in a rotatablemanner; a circular-arc guide groove 882 b around which the inner cable892 is coiled; and a hole section 882 c on which is fixed the terminalmember 892 a of the inner cable 892.

FIG. 54 is a schematic perspective view showing the area of thereclining seat 61 on which the take-up member 880 is fixed. As shown inFIG. 54, the first plate 897 is attached to the backrest 62, and thesecond plate 898 is attached to the seat portion 63. Through use of anunillustrated bolt, the case 881 of the take-up member 880 is secured tothe mount hole 897 a of the first plate 897 through the mount hole 881a. In this case, the mount hole 881 a of the case 881 is formed into theshape of an elongated hole, and hence the case 881 can be secured evenif there is an offset between the mount hole 897 of the first plate 897to which the case 881 is secured and the mount hole 881 a. Accordingly,the case 881 can allow offset of the pitch at which the case 881 issecured to the backrest 62. Therefore, formation of a mount hole doesnot require a high degree of dimensional precision, thereby enabling areduction in manufacturing costs.

A bolt 898 b having a width defined by two flat surfaces is used for thesecond plate 898. In response to the width defined by two flat surfacesof the bolt 898 b, as shown in FIG. 53, the lever 883 is provided withan elongated hole 883 c. The lever 883 is secured to the bolt 898 b in astationary manner by means of the nut 885.

As shown in FIGS. 55 and 56, the seat belt retractor 800 comprises thesubstantially cylindrical bobbin 2, around which a webbing 70 is wound;the take-up shaft 4 which is inserted into the bobbin 2, is rotativelysupported by means of the retractor base 801, and has at one end thereof(i.e., on the right-side of the take-up shaft 4 shown in FIG. 56) thelatch plate 4 a formed from a ratchet wheel; and the emergency lockmechanism 300, all of which are identical to those described withreference to the preceding embodiments. The webbing 70 withdrawn fromthe retractor 800 by way of the slot 64 formed in the backrest 62restraints the occupant.

The retractor base 801 mounted on a frame member (not shown) of thebackrest 62 is formed from a metal plate through press molding such thatthe majority of the retractor base 801 assumes a substantially angularC-shaped cross section. The take-up shaft 4 fitted into the bobbin 2 isrotatable and sandwiched between the sides plates 801 a and 801 b of theretractor base 801. The end of the take-up shaft 4 that passes throughthe side plate 1 b of the retractor base 801 is provided with a knowntake-up device (not shown). At all times, the take-up device urges thebobbin 2, in the direction in which the webbing 70 is taken up, by wayof the take-up shaft 4.

The vehicle body acceleration sensor 232 according to the secondembodiment is provided below the ratchet wheel 19 constituting theemergency lock mechanism 300.

As shown in FIGS. 55 and 56, the vehicle body acceleration sensor 832according to the eighth embodiment comprises a sensor arm 831, a sensorcase 836, an inertial body 833, a case support member 837, andtransmission means 839.

The sensor case 836 comprises an inertial body support surface 836 a onwhich the inertial body 833 is placed, and an arm support section 836 bthat rotatively supports the sensor arm 831. The inertial body supportsurface 836 a of the sensor case 836 is formed into the shape of a fanhaving its center extending below the main portion of the fan. As shownin FIG. 55, the case support member 837 comprises a case support section840 into which the sensor case 836 is removably fitted; a pivot section841 which extends upward from one side of the case support section 840and is rotatably supported by the retractor base 801; and a jointsection 842 to be connected to the terminal member 892 b of the innercable 892. Further, the case support member 837 has a take-up surface844 which continues from the joint section 842 and is positionedconcentrically and in line with the take-up shaft 4.

The pivot section 841 of the case support member 837 is supported so asto be able to pivot about the pivot axis T of the take-up shaft 4. Whenthe backrest 62 is reclined by means of the transmission means 890connected to the joint section 842, the case support member 837 ispivoted in synchronization with the reclining action of the backrest 62,thereby adjusting the sensor case 836 of the vehicle body accelerationsensor 832 to an appropriate orientation.

As shown in FIG. 55, a pin section 831 a provided at the base end of thesensor arm 831 is rotatively supported by the sensor case 836. While thesensor case 836 is attached to the retractor 801, the sensor arm 831 canbe pivoted about the pin section 831 a thereof and can switch between afirst position—where a leading edge 831 b engages the teeth 19 a of theratchet wheel 19 to thereby prevent the take-up shaft 4 from rotating inthe direction in which the webbing is drawn-out—and a secondposition—where the leading edge 831 b is disengaged from the teeth 19 ato thereby prevent actuation of the lock means.

When the leading edge 831 b of the sensor arm 831 engages the teeth 19 aof the ratchet wheel 19, the ratchet wheel 19 rotates so as to lagbehind the take-up shaft 4. As a result, the pole 11 engages the latchplate 4 a by way of the latch cup 13, thereby preventing rotation of thetake-up shaft 4 in the direction in which the webbing is drawn-out.Further, the inertial body 833 is placed on the inertial body supportsurface 836 a. Upon receipt of a velocity change greater than apredetermined magnitude, the inertial body 833 moves in relation to theinertial body support surface 836 a, thereby moving to the firstposition the sensor arm 831 that remains in contact with the outside ofthe inertial body 833.

FIG. 57A shows the backrest 62 when set to the most forwardly reclinedposition within the range of reclining action of the backrest in whichan occupant can use the seat. FIG. 57B is a side view showing thetake-up member 880 from which a cover 886 is removed when the backrest62 is in the position shown in FIG. 57A. FIG. 57C is a side view showingthe retractor 800 when the backrest 62 is in the position shown in FIG.57A.

When the backrest 62 shown in FIG. 57A is reclined backward from themost forwardly reclined position within the range of reclining action ofthe backrest in which an occupant can use the seat, the slider 882 ispulled by the inner cable 892 and attempts to pivot in acounterclockwise direction. However, the slider 882 is pressed by theprotuberance 883 b and remains stationary.

As shown in FIG. 57B, as the backrest 62 is reclined, the case 881pivots in a counterclockwise direction in conjunction with the backrest62. The large diametrical section 893 of the outer tube 894 housed inthe groove section 881 c of the case 881 pivots in a counterclockwisedirection, whereby the slider-side end of the inner cable 892 protrudesfrom the outer tube 894 in the direction of Y1 and is coiled around theguide groove 882 b of the slider 882.

As shown in FIG. 57C, the retractor-side end section of the inner cable892 is pulled in the direction of Y. Since the retractor-side endsection of the inner cable 892 is connected to the case support member837 and the inner cable 892 is also moved along the take-up surface 894concentric with the take-up shaft 4, the sensor case 836 retained by thecase support member 837 also pivots in a clockwise direction about thetake-up shaft 4.

If the radius of the inner cable 898 coiled around the guide groove 882b of the slider 882 is set equal to the radius of the inner cable 892coiled around the take-up surface 844 by way of a spring 889, theretractor-side end section of the inner cable 892 is also moved by adistance corresponding to the length of the inner cable 892 coiledaround the slider 882, as a result of reclining of the backrest 62.Therefore, the sensor case 836 is pivoted to an angle corresponding tothe reclining angle of the backrest 62.

Accordingly, since the sensor case 836 is retained in an appropriateorientation regardless of the reclining angle of the backrest 62, thevehicle body acceleration sensor can sense the acceleration of thevehicle body without fail.

FIG. 58A is a side view showing a reclining seat when the backrest is 62reclined to the most backwardly reclined position (i.e., a full-flatposition); FIG. 58B is a side view showing the take-up member 880 fromwhich the cover 886 is removed when the backrest 62 is in the full-flatposition; and FIG. 58C is a side view showing the retractor 800 when thebackrest 62 is in the full-flat position.

As shown in FIG. 58B, the slider-side end section of the inner cable 892is coiled around the guide groove 882 b of the slider 882 until thebackrest 62 becomes fully flat. As a result, as shown in FIG. 58C, thesensor case 836 pivots about the pivot axis T by way of the case supportmember 837 by the amount corresponding to the amount of the inner cable892 being coiled. Further, the spring 889 is coiled around theretractor-side end section of the inner cable 892 and is held in acompressed state at this time.

Consequently, the restoration force of the spring 889 acts on the casesupport member 837 in a counterclockwise direction, thereby also actingon the inner cable 892 in direction X, as shown in FIG. 58C. Theslider-side end section of the inner cable 892 is joined to the slider882, and, as shown in FIG. 58B, the inner cable 892 is subjected to atensile force in the direction of X1. However, since the slider 882 ispressed by the protuberance 883 b of the lever 883, the case supportmember 837 is not rotated in a counterclockwise direction any further,thereby limiting the pivotable range of the sensor case 836.

If the backrest 62 is forwardly reclined beyond the range in which theoccupant can use the seat from the position shown in FIG. 57, the case881 is arranged so as to pivot together with the slider 882 while theprotuberance 881e remains in contact with the slider 882.

FIG. 59A is a side view showing the reclining seat when a backrest isreclined to a forward position beyond a range of reclining angle of thebackrest in which an occupant can use the seat; FIG. 59B is a side viewshowing the take-up member 880 from which the cover 886 is removed whenthe backrest is reclined as shown in FIG. 59A; and FIG. 59C is a sideview showing the retractor 800 when the backrest is reclined as shown inFIG. 59A.

As shown in FIG. 59B, when the backrest 62 is reclined forward, theslider 882 remains in contact with the protuberance 881 e of the case881, and hence pivots in a clockwise direction together with the case881. Since there is no change in a relative position between the slider882 joined to the slider-side end section of the inner cable 892 and thecase 881, the inner cable 892 neither projects nor is withdrawn.

Since the inner cable 892 neither projects nor is withdrawn, as shown inFIG. 59C there is no change in relative position between the retractor800 and the case support member 837 for retaining the sensor case 836.Consequently, within the range in which the occupant cannot use theseat, the emergency lock mechanism 300 is activated as a result ofreclining action of the backrest 62. However, since no occupant uses theseat in this range, no problems arise. Further, since the case member837 is not pivoted meaninglessly, the needless movable range of thesensor case 836 can be eliminated, thereby rendering the retractor 800compact.

FIG. 60 is a schematic side view showing a reclining seat, wherein aseat belt retractor 900 having a vehicle body acceleration sensor 932for use with a seat belt according to an ninth embodiment isincorporated in a backrest.

The seat belt retractor 900 is built in the backrest 62 of the recliningseat 61 mounted on a vehicle body. The backrest 62 is connected to theseat portion 63 so as to be pivotal about a seat reclining pivotextending in the widthwise direction of the vehicle body. According tothe physique of an occupant, the inclination of the backrest 62 isadjusted. A wire lever take-up member 997 constituting a take-up memberof transmission means 990 is secured to the backrest 62, and a wiretake-up member 998 constituting the take-up member of the transmissionmeans 990 is secured to the seat portion 63.

The take-up member 990 constitutes angle sensing means for sensing thereclining angle of the backrest 62 by detection of a relative rotationbetween the wire lever 997 which is disposed on the backrest and pivotstogether with the backrest 62 and the wire take-up member 998 which isdisposed on the seat portion.

As shown in FIG. 61, the wire lever 997 comprises a trench 997 b forhousing a threaded portion 995 a of a joint 995 formed on a lever-sideend section of an outer tuber 994 constituting the transmission means990; a screw receive hole 997 a for housing an adjustment screw 991which is screw-engaged with the threaded portion 995 a; and a mount hole997 c used for securing the wire lever 997 to the backrest 62 (see FIG.62).

As shown in FIG. 63, the wire take-up member 998 comprises a guidegroove 998 b around which is coiled a wire 992 serving as a transmissionmember of the transmission means 990; and a groove 998 c for housing aterminal member 992 a of the wire 992 in a movable fashion. The guidegroove 998 b and the groove 998 c are formed into the shape ofcircular-arc grooves which take as a center of curvature a center axis998 d serving as the pivot of the wire lever 997.

As shown in FIG. 62, the adjustment screw 991 is attached to thethreaded portion 995 a of the joint 995 that is formed on the lever-sideend section of the outer tuber 994 in which the wire 992 is inserted.Through adjustment of the adjustment screw 991 housed in the screwhousing hole 997 a of the wire lever 997 and a nut 993 provided so as toremain in contact with an end 997 d of the wire lever 997, as required,the joint 995 whose threaded portion 995 a is housed in the trench 997 bof the wire lever 997 is actuated in direction of Z, thereby enablingcontrol of length of the portion of wire 92 which projects from thelever-side end section of the outer tuber 994. Through fastening of thenut 993 after adjustment of length of the projection, the lever-side endsection of the outer tuber 994 is secured to the wire lever 997.

As shown in FIGS. 64 and 65, the seat belt retractor 900 comprises thesubstantially cylindrical bobbin 2, around which a webbing 70 is wound;the take-up shaft 4 which is inserted into the bobbin 2, is rotativelysupported by means of a retractor base 901, and has at one end thereof(i.e., on the right-side of the take-up shaft 4 shown in FIG. 65) thelatch plate 4 a formed from a ratchet wheel; and the emergency lockmechanism 300 which is identical to those described with reference tothe preceding embodiments.

The retractor base 901 mounted on a frame member (not shown) of thebackrest 62 is formed from a metal plate through press molding such thatthe majority of the retractor base 901 assumes a substantially angularC-shaped cross section. The take-up shaft 4 fitted into the bobbin 2 isrotatable and sandwiched between both sides plates 901 a and 901 b ofthe retractor base 901. The end of the take-up shaft 4 that passesthrough the side plate 1 b of the retractor base 901 is provided with aknown take-up device (not shown). At all times, the take-up device urgesthe bobbin 2, in the direction in which the webbing 70 is taken up, byway of the take-up shaft 4.

The vehicle body acceleration sensor 932 according to the ninthembodiment is provided below the ratchet wheel 19 constituting theemergency lock mechanism 300.

As shown in FIGS. 64 and 65, the vehicle body acceleration sensor 932according to the ninth embodiment comprises a sensor arm 931, a sensorcase 936, an inertial body 933, a case support member 937, and atransmission means 990.

The sensor case 936 comprises an inertial body support surface 936 a onwhich the inertial body 933 is placed, and an arm support section 936 bthat rotatively supports the sensor arm 931. The inertial body supportsurface 936 a of the sensor case 936 is formed into the shape of a fanhaving its center extending below the main portion of the fan.

As shown in FIG. 64, the case support member 937 comprises a casesupport section 940 in which the sensor case 936 is removably fitted; apivot section 941 which extends upward from one side of the case supportsection 940 and is rotatably supported by the retractor base 901; and ajoint section 942 to be connected to the terminal member 992 b of theinner cable 992.

The pivot section 941 of the case support member 937 is supported so asto be able to pivot about the pivot axis T of the take-up shaft 4. Whenthe backrest 62 is reclined by means of the transmission means 990connected to the joint section 942, the case support member 937 ispivoted in synchronization with the reclining action of the backrest 62,thereby adjusting the sensor case 936 of the vehicle body accelerationsensor 932 in an appropriate orientation.

As shown in FIG. 64, a pin section 931 a provided at the base end of thesensor arm 931 is rotatively supported by the sensor case 936. While thesensor case 936 is attached to the retractor 900, the sensor arm 931 canbe pivoted about the pin section 931 a thereof and can switch between afirst position—where a leading edge 931 b engages the teeth 19 a of theratchet wheel 19 to thereby prevent the take-up shaft 4 from rotating inthe direction in which the webbing is drawn-out—and a secondposition—where the leading edge 931 b is disengaged from the teeth 19 ato thereby prevent actuation of the lock means.

When the leading edge 931 b of the sensor arm 931 engages the teeth 19 aof the ratchet wheel 19, the ratchet wheel 19 rotates so as to lagbehind the take-up shaft 4. As a result, the pole 11 engages the latchplate 4 a by way of the latch cup 13, thereby preventing rotation of thetake-up shaft 4 in the direction in which the webbing is drawn-out.Further, the inertial body 933 is placed on the inertial body supportsurface 936 a. Upon receipt of a velocity change greater than apredetermined magnitude, the inertial body 933 moves in relation to theinertial body support surface 936 a, thereby moving to the firstposition the sensor arm 931 that remains in contact with the outside ofthe inertial body 933.

The foregoing seat belt retractor 900 comprises control means (notshown) for actuating the emergency lock mechanism 300 according to thetaking up of the webbing so that the lock means follows an engagementposition or a disengagement position with respect to the take-up shaft.The control means causes the lock means to engage the take-up shaft,thereby locking rotation of the take-up shaft in the direction in whichthe webbing is drawn-out and actuating an automatic lock mechanism. Thedetailed structure of the automatic lock mechanism is described inJapanese Utility Model Unexamined Publication No. Hei.6-61609 filed bythe present inventor.

The foregoing seat belt retractor 900 is further provided with an endlock mechanism (not shown) which prevents actuation of the emergencylock mechanism 300 when the webbing of greater than a predeterminedlength is already taken up. This end lock mechanism permits the webbingto be readily drawn-out or taken up when no occupant is buckled up. Thedetailed structure of the end lock mechanism is described in JapanesePatent Unexamined Publication No. Hei.10-42015 filed by the presentinventor.

FIG. 66A is a side view showing the reclining seat when the backrest 62is reclined to the most forward position within a range of recliningaction of the backrest in which an occupant can take the seat; FIG. 66Bis a side view showing a wire take-up member 998 when the backrest 62 isreclined as shown in FIG. 66A; and FIG. 66C is a side view showing theretractor 900 when the backrest is reclined as shown in FIG. 66A.

When the backrest 62 shown in FIG. 66A is reclined backward from themost forwardly reclined position within the range of reclining action ofthe backrest in which an occupant can take the seat, the wire lever 997secured to the backrest 62 shown in FIG. 66B is pivoted counterclockwisetogether with the backrest 62. Since the wire 992 is fixed to one end ofthe groove 998 c formed in the wire take-up member 998, the wire lever997 moves in relation to the wire 992. As a result, the wire 992 ispulled from the lever-side end section of the outer tuber 994 and iscoiled around the guide groove 998 b of the wire take-up member 998.

As shown in FIG. 66C, the retractor-side end section of the inner cable992 is pulled in direction of Y. Since the retractor-side end section ofthe wire 992 is connected to the case support member 937 and the wire992 is also moved along the take-up surface 994 concentric with thetake-up shaft 4, the sensor case 936 retained by the case support member937 also pivots in a clockwise direction about the take-up shaft 4.

If the radius of the wire 992 coiled around the guide groove 998 b ofthe wire take-up member 998 is set so as to equal to the radius of thewire 992 coiled around the take-up surface 944, the retractor-side endsection of the wire 992 is also moved by a distance corresponding to thelength of the inner cable 992 coiled around the guide groove 998 b as aresult of reclining of the backrest 62. Therefore, the sensor case 936is pivoted through an angle corresponding to the reclining angle of thebackrest 62.

Accordingly, since the sensor case 936 is retained in an appropriateorientation regardless of the reclining angle of the backrest 62, thevehicle body acceleration sensor can sense the acceleration of thevehicle body without fail.

FIG. 67A is a side view showing a reclining seat when the backrest 62 isreclined to the most reclined position (i.e., a full-flat position);FIG. 67B is a side view showing the wire take-up member 998 when thebackrest 62 is in the full-flat position; and FIG. 67C is a side viewshowing the retractor 900 when the backrest 62 is in the full-flatposition.

As shown in FIG. 67B, the lever-side end section of the wire 992 iscoiled around the guide groove 998 b of the wire take-up member 998until the backrest 62 becomes full flat. As a result, as shown in FIG.67C, the sensor case 936 pivots about the pivot axis T by way of thecase support member 937 by the amount corresponding to the amount of thewire 992 being coiled and is adjusted toward an appropriate orientation.

FIG. 68A is a side view showing a reclining seat when the backrest 62 isreclined from the position shown in FIGS. 66A to 66C; FIG. 68B is a sideview showing the wire take-up member 998 when the backrest 62 is in theposition shown in FIG. 68A; and FIG. 68C is a side view showing theretractor 900 when the backrest 62 is in the position shown in FIG. 68A.

As shown in FIG. 68A, when the backrest 62 is reclined forwardly, thewire lever 997 pivots in a clockwise direction together with thebackrest 62. During the course of reclining of the backrest 62 from thefull flat position to the most forward position within the range inwhich the occupant can take the seat, the wire lever 997 moves inrelation to the terminal member 992 b of the wire 992. However, afterpassage of the most forward position, the terminal member 992 a of thewire 992 moves in cooperation with the wire lever 997 and travels withinthe groove 998 c that takes as the center of radius the pivot of thewire lever 997. As a result, the wire 992 does not protrude from thelever-side end thereof or is not withdrawn from the retractor-side endthereof, thereby preventing the case support member 937 from pivoting insynchronization with the backrest 62.

In the state in which the backrest 62 is reclined forward from the rangein which the occupant can take the seat, i.e., the state in which thesynchronous movement of the vehicle body acceleration sensor 932 iscanceled, the sensor case 936 remains stationary and does not protrudeoutward from the side surface of the retractor base 901. Therefore, theretractor 900 is prevented becoming bulky and can be made compact.

Even when the vehicle body sensor 932 is locked in the foregoingcanceled state, the seat belt is already completely taken up. Further,the vehicle body acceleration sensor is provided with the end lockprevention means, thereby enabling withdrawal of the seat belt andeliminating a difficulty in reclining the backrest upward.

FIG. 69 is a front view showing the seat belt retractor 900 equippedwith a sensor cover 950. As shown in FIG. 69, a spring 951 is attachedto the outer peripheral surface of a sensor cover 950. The spring 951comprises a coil section 951 a, and a leg section 951 b. The leg section951 b is provided with a claw 951 c. The claw 951 c of the spring 951engages a step 937 b of a protuberance 937 a formed on the case supportmember 937, and the tip end of the claw 951 c engages a hole 937C of thecase support member 937, thereby urging the case support member 937 in acounterclockwise direction.

Although the case support member 937 pivots in association with themovement of the wire 992 in the manner as mentioned above, acircular-arc hole 952 which permits insertion of the protuberance of 937of the case support member 937 is formed in the sensor cover 950 so asto permit pivotal movement of the case support member 937. While thecase support member 937 is pulled by means of the wire 992, the casesupport member 937 is urged in a counterclockwise direction by therestoration force of the spring 951, thereby generating tension betweenthe case support member 937 and the wire 992. As a result, even if thecase support member 937 is stopped during its pivotal movement, thevehicle body acceleration sensor 932 is maintained in an appropriatestationary condition.

The groove 998 c of the wire take-up member 998 according to the ninthembodiment is not limited to the shape of a circular arc, and the groove998 c may assume any shape, so long as the shape ensures a region inwhich the wire lever 997 can work in cooperation with the terminalmember 992 a of the wire 992 when pivoting.

FIG. 70 is a schematic side view showing a reclining seat, wherein aseat belt retractor 1000 having a vehicle body acceleration sensor 1032for use with a seat belt according to a tenth embodiment is incorporatedin a backrest.

The seat belt retractor 1000 is built in the backrest 62 of thereclining seat 61 mounted on a vehicle body. The backrest 62 isconnected to the seat portion 63 so as to be pivotal about a seatreclining pivot extending in the widthwise direction of the vehiclebody. According to the physique of an occupant, the inclination of thebackrest 62 is adjusted.

As shown in FIGS. 71 and 72, the seat belt retractor 1000 comprises thesubstantially cylindrical bobbin 2 around which a webbing 70 is wound;the take-up shaft 4 which is inserted into the bobbin 2, is rotativelysupported by means of the retractor base 1001, and has at one endthereof (i.e., on the right-side of the take-up shaft 4 shown in FIG.72) the latch plate 4 a formed from a ratchet wheel; and the emergencylock mechanism 300 which is identical to those described with referenceto the preceding embodiments.

The retractor base 1001 mounted on a frame member (not shown) of thebackrest 62 is formed from a metal plate through press molding such thatthe majority of the retractor base 1001 assumes a substantially angularC-shaped cross section. The take-up shaft 4 fitted into the bobbin 2 isrotatable and sandwiched between both sides plates 1001 a and 1001 b ofthe retractor base 1001. The end of the take-up shaft 4 that passesthrough the side plate 1 b of the retractor base 1001 is provided with aknown take-up device (not shown). At all times, the take-up device urgesthe bobbin 2, in the direction in which the webbing 70 is taken up, byway of the take-up shaft 4.

The vehicle body acceleration sensor 1032 according to the tenthembodiment is provided below the ratchet wheel 19 constituting theemergency lock mechanism 300.

As shown in FIGS. 71 and 72, the vehicle body acceleration sensor 1032according to the tenth embodiment comprises a sensor arm 1031, a sensorcase 1036, an inertial body 1033, a case support member 1037, and atransmission means 1090.

The sensor case 1036 comprises an inertial body support surface 1036 aon which the inertial body 1033 is placed, and an arm support section1036 b that rotatively supports the sensor arm 1031. The inertial bodysupport surface 1036 a of the sensor case 1036 is formed into the shapeof a fan having its center extending below the main portion of the fan.

The case support member 1037 comprises a case support section 1040 inwhich the sensor case 1036 is removably fitted; a pivot section 1041which extends upward from one side of the case support section 1040 andis rotatably supported by the retractor base 1001; and a joint section1042 to be connected to the terminal member 1092 b of the inner cable1092.

The pivot section 1041 of the case support member 1037 is supported soas to be able to pivot about the pivot axis T of the take-up shaft 4.When the backrest 62 is reclined by means of the transmission means 1090connected to the joint section 1042, the case support member 1037 ispivoted in synchronization with the reclining action of the backrest 62,thereby adjusting the sensor case 1036 of the vehicle body accelerationsensor 1032 in an appropriate orientation.

As shown in FIG. 71, a pin section 10 provided at the base end of thesensor arm 1031 is rotatively supported by the sensor case 1036. Whilethe sensor case 1036 is attached to the retractor 1000, the sensor arm1031 can be pivoted about the pin section 1031 a thereof and can switchbetween a first position—where a leading edge 1031 b engages the teeth19 a of the ratchet wheel 19 to thereby prevent the take-up shaft 4 fromrotating in the direction in which the webbing is drawn-out—and a secondposition—where the leading edge 1031 b is disengaged from the teeth 19 ato thereby prevent actuation of the lock means.

When the leading edge 1031 b of the sensor arm 1031 engages the teeth 19a of the ratchet wheel 19, the ratchet wheel 19 rotates so as to lagbehind the take-up shaft 4. As a result, the pole 11 engages the latchplate 4 a by way of the latch cup 13, thereby preventing rotation of thetake-up shaft 4 in the direction in which the webbing is drawn-out.Further, the inertial body 1033 assumes a spherical shape and is placedon the inertial body support surface 1036 a. Upon receipt of a velocitychange greater than a predetermined magnitude, the inertial body 1033moves in relation to the inertial body support surface 1036 a, therebymoving to the first position the sensor arm 1031 that remains in contactwith the outside of the inertial body 1033.

FIG. 73 is an enlarged fragmentary view showing the reclining seat 61according to the tenth embodiment. As shown in FIG. 73, the backrest 62is connected to the seat portion 63 so as to be pivotal about a seatreclining pivot (a seat reclining pivot) 1077 extending in the widthwisedirection of the vehicle body. According to the physique of an occupant,the inclination of the backrest 62 is adjusted. A first plate 1071 isattached to the backrest 62,and a second plate 1072 is attached to theseat portion 63.

A first mount hole 1071 a is formed in the first plate 1071 for thepurpose of attaching the first plate 1071 to the backrest 62. A secondmount hole 1072 a and a third mount hole 1072 b are formed in the secondplate 1072 for the purpose of attaching the second plate 1072 to theseat portion 63. A circular cap 1075 is provided at the end surface ofthe seat reclining pivot 1077 that passes through the first and secondplates 1071 and 1072.

FIG. 74 shows a schematic side view showing angle sensing means 1070 forsensing the reclining angle of the backrest according to the tenthembodiment. As shown in FIG. 74, the angle sensing means 1070constituting the transmission means 1090 comprises a take-up member 1080for sensing the reclining angle of the backrest 62 by detection ofrelative turning movement between a case 1081 which pivots inconjunction with the backrest 62 and a slider 1082 which is provided inthe seat portion by way of a lever 1083 fixed to a seat portion fixturemember 1098.

Through detection of relative turning movement between the case 1081 andthe seat portion fixture member 1098, the reclining angle of thebackrest 62 is sensed, whereby the case support member 1037 is pivotedin synchronization with the reclining action of the backrest 62 by wayof the inner cable 1092. A first mount hole 1097 a is formed in abackrest fixing member 1097 formed integrally with the case 1081, and asecond mount hole 1098 a and a third mount hole 1098 b are formed in thesear portion fixture member 1098.

A pin member 1099—which serves as a pivot of the angle sensing means1070 provided concentric with the seat reclining pivot of the backrest62—is attached to the seat portion fixture member 1098. The pin member1099 assuming the shape of a cylindrical protrude is fitted into the cap1075 of the seat reclining pivot 1077. The pin member 1099 may be formedintegrally with the seat portion fixture member 1098. The tip end of thepin member 1099 is chamfered so as to become readily enter the cap 1075.

Centering takes place through use of the pin member 1099 and the cap1075. Subsequently, the first mount hole 1097 a of the backrest fixingmember 1097 is fitted to the first mount hole 1071 a of the first plate1071; the second mount hole 1098 a of the seat portion fixture member1098 is fitted to the second mount hole 1072 a of the second plate 1072;and the third mount hole 1098 b of the seat portion fixture member 1098is fitted to the third mount hole 1072 b of the second plate 1072. Theseat portion fixture member 1098, the first plate 1071, and the secondplate 1072 are fixed to the backrest 62 and the seat portion 63 by meansof bolts.

Since the pin member 1099 of the angle sensing means 1070 is fitted intothe cap 1075 of the seat reclining pivot 1077, the seat reclining pivotof the backrest 62 can be brought in alignment with the pivot axis ofthe angle sensing means 1070.

Thus, since there is match between the reclining angle of the backrest62 and the pivoting angle of the angle sensing means 1070, thetransmission means 1090 can correctly adjust the orientation of thesensor case 1036 of the vehicle body acceleration sensor 1032.

Further, there are required only provision of the pin member 1099 to theseat portion fixture member 1098 which fits to the cap 1075 andprovision of the cap 1075 to the seat reclining pivot 1077, therebypreventing an increase in manufacturing costs.

Both the angle sensing means 1070 and the reclining seat 61 are formedfrom a plurality of components, and offsets of the pitch inevitablyarise for reasons of dimensional tolerance and clearance among movingparts. However, if the angle sensing means 1070 is offset, the recliningangle of the backrest cannot be detected correctly.

However, the first mount hole 1097 a of the backrest fixing member 1097,the second mount hole 1098 a of the seat portion fixture member 1098,and the third mount hole 1098 b of the seat portion fixture member 1098are set so as to assume a hole diameter greater than the diameter of abolt. Even if there are offsets between the first mount hole 1097 a andthe first mount hole 1071 a; the second mount hole 1098 a and the secondmount hole 1072 a; and the third mount hole 1098 b and the third mounthole 1072 b, the seat portion fixture member 1098, the first plate 1071,and the second plate 1072 are fixed to the backrest 62 and the seatportion 63. The first mount hole 1097 a, the second mount hole 1098 a,and the third mount hole 1098 b may be formed into the shape of anelongated hole.

Accordingly, the angle sensing means 1070 can allow offset of the pitchat which the angle sensing means 1070 is secured to the backrest 62.Therefore, formation of a mount hole does not require a high degree ofdimensional precision, thereby enabling a reduction in manufacturingcosts.

As shown in FIG. 75, the take-up member 1080 comprises a case 1081 whichhouses an inner cable 1092 serving as a transmission member oftransmission means 1090 and has a backrest fixing member 1097; asubstantially-fan-shaped slider 1082 around which the inner cable 1092is coiled; a lever 1083 which hinders pivotal movement of the slider1082 by means of a protuberance 1083 b and has a cylindrical portion1083 a serving as the pivot of the slider 1082; and a nut 1085 whichenables fixing of the lever 1083 to a protuberance 1098 t of the seatportion fixture member 1098 by way of the washer 1084. Here, the lever1083 may be fixed by caulking the protuberance 1098 t of the seatportion fixture member 1098 without use of the washer 1084 and the nut1085.

The case 1081 comprises a trench 1081 b for housing a threaded portion1095 a of a joint 1095 formed on a seat-reclining-pivot-side end sectionof an outer tuber 1094 constituting the transmission means 1090; a screwreceive hole 1081 a for housing an adjustment screw 1091 which isscrew-engaged with the threaded portion 1095 a; a mount hole 1081 c inwhich the cylindrical section 1083 a of the lever 1083; and aprotuberance 1081 e for preventing pivotal movement of the slider 1082.

The slider 1082 comprises a hollow cylinder 1082 a pivotally supportedby the cylindrical portion 1083 a of the lever 1083; a circular-arcshaped guide groove 1082 b around which the inner cable 1092 is coiled;and a hole 1082 c in which a terminal end member 1092 a of the innercable 1092 is secured.

Further, the transmission means 1090 comprises an adjustment screw 1091and a nut 1093, both of which are attached to the threaded section 1095a of the joint 1095. Through adjustment of the adjustment screw 1091housed in the screw receive hole 1081 a of the case 1081 and theadjustment screw 1093 provided so as to be in contact with an endsection 1081 f of the case 1081, as required, the joint 1095 whosethreaded section 1095 a is housed in the trench 1081 b of the case 1081is moved in direction of Z, thereby enabling control of projection ofthe inner cable 1092 whose one end is fixed to the joint 1095.

When the backrest 62 shown in FIG. 70 is reclined backward, the slider1082 is pulled by the inner cable 1092 and attempts to pivot in acounterclockwise direction. However, since the slider 1082 is pressed bythe protuberance 1083 b of the lever 1083, the slider 1082 cannot pivot.In contrast, as the backrest 62 is reclined, the case 1081 pivots in acounterclockwise direction together with the backrest 62, and hence theend sections of the slider 1082 and the inner cable 1092 remainstationary. When the case 1081 pivots in a counterclockwise direction,the inner cable 1092 protrudes and is coiled around the guide groove1082 b of the slider 1082.

As shown in FIG. 71, the inner cable 1092 is pulled in direction of Y.Since one end of the inner cable 1092 is joined to the case supportmember 1037 and the inner cable 1092 per se travels along the take-upsurface 1044 concentric with the take-up shaft 4, the center case 1036retained by the case support member 1037 also pivots in a clockwisedirection about the take-up shaft 4.

If the radius of the wire 1092 coiled around the guide groove 1082 b ofthe slider 1082 is set so as to equal to the radius of the inner cable1092 coiled around the take-up surface 1044 by way of the spring 1089,the retractor-side end section of the inner cable 1092 moves over thedistance corresponding to the length of the inner cable 1092 beingcoiled around the slider 1082 as a result of reclining of the backrest62, and hence the sensor case 1036 pivots through an angle correspondingto the reclining angle of the backrest 62.

Accordingly, since the sensor case 1036 is retained in an appropriateorientation (i.e., an upright position) regardless of the recliningangle of the backrest 62, the vehicle body acceleration sensor can sensethe acceleration of the vehicle body without fail.

FIGS. 76 and 77 show a modification of the angle sensing means accordingto the tenth embodiment.

As shown in FIG. 76, as in the case with the tenth embodiment, thebackrest 62 is connected to the seat portion 63 so as to be able topivot about a seat reclining pivot 1177. The backrest 62 has a firstplate 1171, and a second plate 1172 is attached to the seat portion 63.

The first plate 1171 has a first mount hole 1071 a used for attachingthe first plate 1171 to the backrest 62, and the second plate 1172 has asecond mount hole 1172 a and a third mount hole 1172 b, both of whichare used for attaching the second plate 1172 to the seat portion 63. Acircular cap 1175 is provided at the end surface of the seat recliningpivot 1177 that passes through the first and second plates 1171 and1172.

As shown in FIG. 77, angle sensing means 1170 for sensing the recliningangle of the backrest comprises a take-up member 1180 for sensing thereclining angle of the backrest 62 by detection of relative turningmovement between the case 1081 which pivots in conjunction with thebackrest 62 and the slider 1082 which is provided in the seat portion byway of the lever 1183 fixed to a seat portion fixture member 1098.

Through detection of relative turning movement between the case 1081 andthe seat portion fixture member 1198, the reclining angle of thebackrest 62 is sensed, whereby the case support member 1037 is pivotedin synchronization with the reclining action of the backrest 62 by wayof the inner cable 1092. A first mount hole 1097 a is formed in abackrest fixing member 1097 formed integrally with the case 1081, and asecond mount hole 1198 a and a third mount hole 1198 b are formed in thesear portion fixture member 1198.

A pin member 1199—which serves as a pivot of the angle sensing means1170 provided concentric with the seat reclining pivot of the backrest62—is attached to the seat portion fixture member 1198.

A circular hole 1199 a serving as an indentation is formed in the pinmember 1199 and fittingly receives the cap 1175 of the seat recliningpivot 1177.

Centering takes place through use of the pin member 1199 a and the cap1175. Subsequently, the first mount hole 1097 a of the backrest fixingmember 1097 is fitted to the first mount hole 1171 a of the first plate1171; the second mount hole 1198 a of the seat portion fixture member1198 is fitted to the second mount hole 1172 a of the second plate 1172;and the third mount hole 1198 b of the seat portion fixture member 1198is fitted to the third mount hole 1172 b of the second plate 1172. Theseat portion fixture member 1198, the first plate 1171, and the secondplate 1172 are fixed to the backrest 62 and the seat portion 63 by meansof bolts. The second mount hole 1198 a and the third mount hole 1198 bare also set so as to assume a hole diameter greater than the diameterof the bolt.

Since the hole 1199 a of the angle sensing means 1170 fittingly receivesthe cap 1175 of the seat reclining pivot 1177, the seat reclining pivotof the backrest 62 can be brought in alignment with the pivot axis ofthe angle sensing means 1170.

Thus, since there is match between the reclining angle of the backrest62 and the pivoting angle of the angle sensing means 1170, thetransmission means 1090 can correctly adjust the orientation of thesensor case 1036 of the vehicle body acceleration sensor 1032.

The shapes of the protrusion and the recess formed in the seat portionof the backrest and the pivot of the angle sensing means according tothe embodiments are not limited to circular shapes or other shapesmentioned with reference to the embodiments. Polygonal shapes or othershapes may be employed, so long as the shapes enable fitting ofelements.

The lock means, the sensor arm, the sensor case, and the inertial bodyaccording to the present invention mentioned with reference to theembodiments are not in configuration to the examples mentioned in thepreceding embodiments. It goes without saying that they may be modified,as required.

For instance, although in the previous embodiments although the pivot ofthe sensor case is brought into alignment with the rotation center ofthe take-up shaft, the sensor case may be pivotally supported on theretractor base in a position outside the rotation center of the take-upshaft.

Further, although the sensor arm is attached to the sensor case in theembodiments, the sensor arm may be pivotally supported on the retractorbase apart from the sensor case, so long as the pivot of the sensor casepasses through the center of the spherical inertial body.

Further, in place of the latch plate constituting the lock means, theremay be employed a configuration in which a pole meshes internal teeth ofa retractor base.

The vehicle body acceleration sensor for use with a seat belt accordingto the present invention is not limited to the embodiments in terms of aspecific configuration of the transmission means for pivoting the sensorcase in synchronization with the reclining action of the backrest and astructure for incorporating the sensor case into the retractor base, andcan be modified, as required, within the scope of the invention.

INDUSTRIAL APPLICABILITY

As has been described above, a vehicle body acceleration sensor for usewith a seat belt according to the present invention is useful as avehicle body acceleration sensor for use with a seat belt which isattached to a backrest of a reclining seat. Particularly, the sensor issuitable when it is attached to a retractor fixed in a backrest of areclining seat which is reclined from the maximum forward position tothe full flat position.

What is claimed is:
 1. A vehicle body acceleration sensor for use with aseat belt comprising: a sensor case which is movably supported by aretractor base attached to a backrest of a vehicle reclining seat; asensor arm which is pivotally supported by one of the sensor case andthe retractor base in such a way as to shift between a first positionwhere lock means is activated so as to prevent rotation of a take-upshaft, around which a webbing is wound, in a direction in which thewebbing is drawn-out and a second position where the lock means isdeactivated; an inertial body which moves in relation to an inertialbody support surface of the sensor case upon receipt of a velocitychange greater than a predetermined magnitude to thereby move the sensorarm to the first position; and transmission means for pivoting thesensor case in synchronization with reclining action of the backrest insuch a way as to retain the inertial body support surface in anappropriate orientation regardless of reclining angle of the backrest,wherein the lock means is activated by means of movement of the inertialbody when an acceleration of predetermined magnitude acts on the vehiclebody; wherein the transmission means comprises a transmission memberwhich can be wrapped around a take-up member provided concentrically andin line with the seat reclining pivot of the backrest, and the sensorcase is pivoted in agreement with the amount of the transmission memberwhich is wrapped around the take-up member in association with thereclining action of the backrest; wherein when the backrest is reclinedforwardly beyond an area which enables an occupant to use the seat, thetransmission member is prevented from being wrapped around the take-upmember.
 2. A vehicle body acceleration sensor for use with a seat beltcomprising: a sensor case which is movably supported by a retractor baseattached to a backrest of a vehicle reclining seat; a sensor arm whichis pivotally supported by one of the sensor case and the retractor basein such a way as to shift between a first position where lock means isactivated so as to prevent rotation of a take-up shaft, around which awebbing is wound, in a direction in which the webbing is drawn-out and asecond position where the lock means is deactivated; an inertial bodywhich moves in relation to an inertial body support surface of thesensor case upon receipt of a velocity change greater than apredetermined magnitude to thereby move the sensor arm to the firstposition; and transmission means for pivoting the sensor case insynchronization with reclining action of the backrest in such a way asto retain the inertial body support surface in an appropriateorientation regardless of reclining angle of the backrest, wherein thelock means is activated by means of movement of the inertial body whenan acceleration of predetermined magnitude acts on the vehicle body,wherein the transmission means comprises a synchronous movementcancellation mechanism capable of canceling the movement of the sensorcase which is in synchronization with the reclining action of thebackrest.
 3. The vehicle body acceleration sensor according to claim 2,wherein the transmission means comprises a transmission member which canbe wrapped around a take-up member provided concentrically and in linewith the seat reclining pivot of the backrest, and the sensor case ispivoted in agreement with the amount of the transmission member which iswrapped around the take-up member in association with the recliningaction of the backrest.
 4. The vehicle body acceleration sensoraccording to claim 3, wherein an end member of the transmission memberfacing the vehicle body acceleration sensor is wrapped about the take-upmember, and the take-up member pivots the sensor case in agreement withthe amount of the transmission member that is wrapped around the take-upmember, by causing the winding radius of the end member of thetransmission member facing the take-up member to match the windingradius of the end member of the transmission member facing the vehiclebody acceleration sensor.
 5. A vehicle body acceleration sensor for usewith a seat belt comprising: a sensor case which is movably supported bya retractor base attached to a backrest of a vehicle reclining seat; asensor arm which is pivotally supported by one of the sensor case andthe retractor base in such a way as to shift between a first positionwhere lock means is activated so as to prevent rotation of a take-upshaft, around which a webbing is wound, in a direction in which thewebbing is drawn-out and a second position where the lock means isdeactivated; an inertial body which moves in relation to an inertialbody support surface of the sensor case upon receipt of a velocitychange greater than a predetermined magnitude to thereby move the sensorarm to the first position; and transmission means for pivoting thesensor case in synchronization with reclining action of the backrest insuch a way as to retain the inertial body support surface in anappropriate orientation regardless of reclining angle of the backrest,wherein the lock means is activated by means of movement of the inertialbody when an acceleration of predetermined magnitude acts on the vehiclebody; wherein the transmission means comprises: angle sensing means forsensing the reclining angle of the backrest by detection of relativeturning movement between a member which is provided on the backrest andpivots in conjunction with a backrest and a member which is provided ina seat portion; and a seat pivot shaft placed in line with the seatreclining pivot of the backrest and a pivot shaft of the angle sensingmeans being provided concentrically and in line with the seat recliningpivot of the backrest, the pivot shafts having irregularities which meshwith each other.
 6. The vehicle body acceleration sensor according toclaim 5, wherein holes used for mounting said angle sensing means areformed so as to be large enough to allow offset of the pitch at whichthe angle sensing means is attached to the mount section of a seatportion.
 7. A vehicle body acceleration sensor for use with a seat beltcomprising: a sensor case which is movably supported by a retractor baseattached to a backrest of a vehicle reclining seat; a sensor arm whichis pivotally supported by one of the sensor case and the retractor basein such a way as to shift between a first position where lock means isactivated so as to prevent rotation of a take-up shaft, around which awebbing is wound, in a direction in which the webbing is drawn-out and asecond position where the lock means is deactivated; an inertial bodywhich moves in relation to an inertial body support surface of thesensor case upon receipt of a velocity change greater than apredetermined magnitude to thereby move the sensor arm to the firstposition; and transmission means for pivoting the sensor case insynchronization with reclining action of the backrest in such a way asto retain the inertial body support surface in an appropriateorientation regardless of reclining angle of the backrest, wherein thelock means is activated by means of movement of the inertial body whenan acceleration of predetermined magnitude acts on the vehicle body;wherein the transmission means includes: a cam plate whose cam surfaceextends in the circumferential direction from a seat reclining pivot ofthe backrest, and a transmission member which follows the cam surface ofthe cam plate and pivots the sensor case in conjunction with thereclining action of the backrest.
 8. The vehicle body accelerationsensor according to claim 7, wherein the cam surface of the cam platecomprises: a synchronous movement area in which the sensor case ispivoted in synchronization with the reclining action of the backrestwithin only the optimum working range of the seat belt, andnon-synchronous movement areas in which the sensor case is not pivotedin synchronization with the reclining action of the backrest.
 9. Thevehicle body acceleration sensor according to claim 7, wherein a camcontact section formed on a cam-plate-side end section of thetransmission member which moves back and forth toward the cam surface ofthe cam plate is set so as to move back and forth in such a direction asto impart an optimum pressing force on the entire surface of the camsurface with which the cam contact section makes slidable, contact. 10.The vehicle body acceleration sensor according to claim 7, wherein thecam plate is fixed on a seat portion of the reclining seat, and acam-plate-side end section of the transmission member is fixed on thebackrest so as to be able to move back and forth toward the cam surfaceof the cam plate.
 11. The vehicle body acceleration sensor according toclaim 7, wherein said cam plate has an inner peripheral cam surface andextends in the circumferential direction of the seat reclining pivot ofthe backrest, wherein said transmission means further comprises afollower which is provided on the inner peripheral cam surface of thecam plate so as to be able to move back and forth, and wherein saidtransmission member has a cam-plate-side end section joined to thefollower and a retractor-side end section joined to said sensor case andwhich transmits the forward and backward movement of the follower tosaid sensor case.
 12. The vehicle body acceleration sensor according toclaim 11, wherein the inner peripheral cam surface of the cam plate isprovided with only a synchronous movement area in which the sensor caseis pivoted in synchronization with the reclining action of the backrestwithin only the optimum working range of the seat belt.
 13. The vehiclebody acceleration sensor according to claim 11, wherein the follower hasa roller which moves over the inner peripheral cam surface in arotatable manner, and hence frictional resistance between the innerperipheral cam surface and the follower can be reduced, thereby enablingsmooth forward and backward movement of the follower.
 14. The vehiclebody acceleration sensor according to claim 11, wherein the cam plate ismounted on a seat portion of the reclining seat, and the follower isfixed on the backrest so as to be able to move back and forth along theinner peripheral cam surface of the cam plate.
 15. A vehicle bodyacceleration sensor for use with a seat belt comprising: a sensor casewhich is movably supported by a retractor base attached to a backrest ofa vehicle reclining seat; a sensor arm which is pivotally supported byone of the sensor case and the retractor base in such a way as to shiftbetween a first position where lock means is activated so as to preventrotation of a take-up shaft, around which a webbing is wound, in adirection in which the webbing is drawn-out and a second position wherethe lock means is deactivated; an inertial body which moves in relationto an inertial body support surface of the sensor case upon receipt of avelocity change greater than a predetermined magnitude to thereby movethe sensor arm to the first position; and transmission means forpivoting the sensor case in synchronization with reclining action of thebackrest in such a way as to retain the inertial body support surface inan appropriate orientation regardless of reclining angle of thebackrest, wherein the lock means is activated by means of movement ofthe inertial body when an acceleration of predetermined magnitude actson the vehicle body; wherein the transmission means comprises: a slidemember movably disposed in a seat portion of the reclining seat; a camplate which causes the slide member to advance or recede within only thepivotable range of the sensor case according to the reclining angle ofthe backrest; and a flexible transmission member, one end of which isconnected to the slide member and the other end of which is connected tothe sensor case and which transmits the movement of the slide member tothe sensor case.
 16. A vehicle body acceleration sensor for use with aseat belt comprising: a sensor case which is movably supported by aretractor base attached to a backrest of a vehicle reclining seat; asensor arm which is pivotally supported by one of the sensor case andthe retractor base in such a way as to shift between a first positionwhere lock means is activated so as to prevent rotation of a take-upshaft, around which a webbing is wound, in a direction in which thewebbing is drawn-out and a second position where the lock means isdeactivated; an inertial body which moves in relation to an inertialbody support surface of the sensor case upon receipt of a velocitychange greater than a predetermined magnitude to thereby move the sensorarm to the first position; and transmission means for pivoting thesensor case in synchronization with reclining action of the backrest insuch a way as to retain the inertial body support surface in anappropriate orientation regardless of reclining angle of the backrest,wherein the lock means is activated by means of movement of the inertialbody when an acceleration of predetermined magnitude acts on the vehiclebody; wherein the transmission means comprises: a transmission memberwhich is actuated in synchronization with the reclining action of thebackrest; and a synchronous movement cancellation mechanism which isinterposed at least between a retractor-side joint section of saidtransmission member and the sensor case and which prevents the sensorcase from moving in synchronization with the reclining action of thebackrest when the backrest is reclined beyond an optimum working rangeof the seat belt.
 17. The vehicle body acceleration sensor according toclaim 16, wherein the synchronous movement cancellation mechanismcomprises: a slider which is joined to the sensor case by means of aretractor-side end section of the transmission member and has a range ofmovement limited to the pivotable range of the sensor case that is setto the optimum working range of the seat belt; and an elastic memberwhich is interposed between the slider and a retractor-side jointsection of the transmission member and which is resiliently deformablein the direction of movement of the slider upon receipt of a load ofgreater than a predetermined value.
 18. The vehicle body accelerationsensor according to claim 16, wherein the synchronous movementcancellation mechanism comprises: a gear with a cam which engages with aretractor-side joint section of the transmission member and is rotated;and the sensor case which follows the cam of the gear and pivots withina pivotable range which is set so as to correspond to the optimumworking range of the seat belt.